Code to import WordPress dump / backup file to NSemble. Create a new Console app, add the following files, and add these as links: BlogPost.cs, Constants.cs, DynamicContent.cs, NSembleUserAuthentication.cs, PostComments.cs, User.cs

DynamicContentHelpers.cs

using System;
using System.Collections.Generic;
using System.Globalization;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;
using System.Web;
using NSemble.Core.Models;

namespace NSemble.Core.Extensions
{
    public static class DynamicContentHelpers
    {
        public static string TitleToSlug(string title)
        {
            // 2 - Strip diacritical marks using Michael Kaplan's function or equivalent
            title = RemoveDiacritics(title);

            // 3 - Lowercase the string for canonicalization
            title = title.ToLowerInvariant();

            // 4 - Replace all the non-word characters with dashes
            title = ReplaceNonWordWithDashes(title);

            // 1 - Trim the string of leading/trailing whitespace
            title = title.Trim(' ', '-');

            return title;
        }


        // http://blogs.msdn.com/michkap/archive/2007/05/14/2629747.aspx
        /// <summary>
        /// Strips the value from any non English character by replacing those with their English equivalent.
        /// </summary>
        /// <param name="value">The string to normalize.</param>
        /// <returns>A string where all characters are part of the basic English ANSI encoding.</returns>
        /// <seealso cref="http://stackoverflow.com/questions/249087/how-do-i-remove-diacritics-accents-from-a-string-in-net"/>
        private static string RemoveDiacritics(string value)
        {
            var stFormD = value.Normalize(NormalizationForm.FormD);
            var sb = new StringBuilder();

            foreach (var t in stFormD)
            {
                var uc = CharUnicodeInfo.GetUnicodeCategory(t);
                if (uc != UnicodeCategory.NonSpacingMark)
                {
                    sb.Append(t);
                }
            }

            return (sb.ToString().Normalize(NormalizationForm.FormC));
        }

        private static string ReplaceNonWordWithDashes(string title)
        {
            // Remove Apostrophe Tags
            title = Regex.Replace(title, "[’'“”\"&]{1,}", "", RegexOptions.None);

            // Replaces all non-alphanumeric character by a space
            var builder = new StringBuilder();
            foreach (var t in title)
            {
                builder.Append(char.IsLetterOrDigit(t) ? t : ' ');
            }

            title = builder.ToString();

            // Replace multiple spaces to a single dash
            title = Regex.Replace(title, @"\s{1,}", "-", RegexOptions.None);

            return title;
        }

        static readonly Regex CodeBlockFinder = new Regex(@"\[code lang=(.+?)\s*\](.*?)\[/code\]", RegexOptions.Compiled | RegexOptions.Singleline);
        static readonly Regex FirstLineSpacesFinder = new Regex(@"^(\s|\t)+", RegexOptions.Compiled);

        private static string GenerateCodeBlock(string lang, string code)
        {
            code = HttpUtility.HtmlDecode(code);
            return string.Format("{0}{1}{0}", Environment.NewLine,
                                 ConvertMarkdownCodeStatment(code)//.Replace("<", "&lt;"), // to support syntax highlighting on pre tags
                                 , lang
                );
        }

        private static string ConvertMarkdownCodeStatment(string code)
        {
            var line = code.Split(new[] { Environment.NewLine }, StringSplitOptions.None);
            var firstLineSpaces = GetFirstLineSpaces(line.FirstOrDefault());
            var firstLineSpacesLength = firstLineSpaces.Length;
            var formattedLines = line.Select(l => string.Format("    {0}", l.Substring(l.Length < firstLineSpacesLength ? 0 : firstLineSpacesLength)));
            return string.Join(Environment.NewLine, formattedLines);
        }

        private static string GetFirstLineSpaces(string firstLine)
        {
            if (firstLine == null)
                return string.Empty;

            var match = FirstLineSpacesFinder.Match(firstLine);
            if (match.Success)
            {
                return firstLine.Substring(0, match.Length);
            }
            return string.Empty;
        }

    }
}

Program.cs

        static void Main(string[] args)
        {
            var reader = new WordPressExportReader();
            var posts = reader.Read(@"C:\wordpress.2013-08-02.xml");

            var redirectsTable = new RedirectsTable();

            using (var store = new DocumentStore {Url = "http://localhost:8080", DefaultDatabase = "NSemble"}.Initialize())
            {
                using (var session = store.OpenSession())
                {
                    var user = new User { UserName = "me@mydomain.com", FirstName = "Foo", LastName = "Bar", Claims = new List<string> { "admin" } };
                    NSembleUserAuthentication.SetUserPassword(user, "password");
                    session.Store(user, "users/" + user.UserName);
                    
                    foreach (var post in posts)
                    {
                        if (post.IsPage)
                        {
                            continue;
                        }

                        var blogPost = new BlogPost
                                           {
                                               AllowComments = true,
                                               CommentsCount = post.Comments.Count,
                                               Content = post.Content,
                                               ContentType = DynamicContentType.Markdown,
                                               Title = post.Title,
                                               Tags = post.Tags,
                                               PublishedAt = post.PublishedAt,
                                               LastEditedAt = null,
                                               PrivateViewingKey = Guid.NewGuid().ToString(),
                                               CurrentState = post.IsDraft ? BlogPost.State.Draft : BlogPost.State.Public,
                                               AuthorId = "users/" + user.UserName,
                                           };

                        var comments = new PostComments();
                        foreach (var c in post.Comments)
                        {
                            comments.Comments.Add(new PostComments.Comment
                                                      {
                                                          Approved = true,
                                                          Author = c.AuthorName,
                                                          Content = c.Content,
                                                          CreatedAt = c.PostedAt,
                                                          Email = c.AuthorEmail,
                                                          UserHostAddress = c.AuthorIP,
                                                          Website = c.AuthorUrl,
                                                          Replies = new List<PostComments.Comment>(),
                                                      });
                        }

                        if (string.IsNullOrWhiteSpace(blogPost.Title) || string.IsNullOrWhiteSpace(blogPost.Content))
                        {
                            blogPost.CurrentState = BlogPost.State.Private;
                        }

                        session.Store(blogPost);
                        session.Store(comments, blogPost.Id + "/comments");

                        if (blogPost.CurrentState == BlogPost.State.Public)
                        {
                            redirectsTable.theTable.Add(
                                string.Format("/blog/{0}/{1}/{2}", post.PublishedAt.Year,post.PublishedAt.Month.ToString("D2"), post.Slug),
                                new RedirectsTable.RedirectCommand
                                    {
                                        HttpStatusCode = HttpStatusCode.MovedPermanently,
                                        NewRoute = string.Format("/blog/{0}/{1}/{3}-{2}", post.PublishedAt.Year, post.PublishedAt.Month.ToString("D2"), post.Slug, blogPost.Id.Substring(blogPost.Id.IndexOf('/') + 1)),
                                    });
                        }
                    }
                    redirectsTable.theTable.Add("/", new RedirectsTable.RedirectCommand {HttpStatusCode = HttpStatusCode.SeeOther, NewRoute = "/blog"});
                    session.Store(redirectsTable, Constants.RedirectsTableDocumentId);

                    session.Store(new Dictionary<string, AreaConfigs>
                                      {
                                          {"/blog", new AreaConfigs { AreaName = "MyBlog", ModuleName = "Blog" }},
                                          {"/", new AreaConfigs { AreaName = "MyContent", ModuleName = "ContentPages" }},
                                          {"/auth", new AreaConfigs { AreaName = "Auth", ModuleName = "Membership" }}
                                      }, Constants.AreasDocumentName);

                    session.SaveChanges();
                }
            }
        }

WordPressExportReader.cs

using System;
using System.Collections.Generic;
using System.Xml;

namespace WordPressExportReader
{
    public class WordPressExportReader
    {
        public List<WordPressPost> Read(string exportPath)
        {
            var doc = new XmlDocument();
            doc.Load(exportPath);
            var manager = new XmlNamespaceManager(doc.NameTable);
            manager.AddNamespace("wp", "http://wordpress.org/export/1.1/");
            manager.AddNamespace("dc", "http://purl.org/dc/elements/1.1/");
            manager.AddNamespace("wfw", "http://wellformedweb.org/CommentAPI/");
            manager.AddNamespace("content", "http://purl.org/rss/1.0/modules/content/");

            var nav = doc.CreateNavigator();

            // Compile a standard XPath expression
            var expr = nav.Compile("rss/channel/item");
            var iterator = nav.Select(expr);

            var results = new List<WordPressPost>();

            while (iterator.MoveNext())
            {
                var p = new WordPressPost();
                switch (iterator.Current.SelectSingleNode("wp:status", manager).Value)
                {
                    case "publish":
                    case "inherit":
                        break;
                    case "trash":
                        continue;
                    case "draft":
                        p.IsDraft = true;
                        break;
                }

                if ("page".Equals(iterator.Current.SelectSingleNode("wp:post_type", manager).Value))
                {
                    p.IsPage = true;
                }

                p.Title = iterator.Current.SelectSingleNode("title").Value;
                p.Content = iterator.Current.SelectSingleNode("content:encoded", manager).Value;
                p.Slug = iterator.Current.SelectSingleNode("wp:post_name", manager).Value;
                p.PublishedAt = DateTimeOffset.Parse(iterator.Current.SelectSingleNode("pubDate").Value);
                p.OriginalUrl = iterator.Current.SelectSingleNode("link").Value;

                var tagsIterator = iterator.Current.Select("category");
                p.Tags = new List<string>();
                while (tagsIterator.MoveNext())
                {
                    p.Tags.Add(tagsIterator.Current.Value);
                }

                p.Comments = new List<WordPressPost.Comment>();
                var commentsIterator = iterator.Current.Select("wp:comment", manager);
                while (commentsIterator.MoveNext())
                {
                    var approved = "1".Equals(commentsIterator.Current.SelectSingleNode("wp:comment_approved", manager).Value);
                    if (!approved) continue;

                    var parent = int.Parse(commentsIterator.Current.SelectSingleNode("wp:comment_parent", manager).Value);
                    var comment = new WordPressPost.Comment
                                       {
                                           AuthorName = commentsIterator.Current.SelectSingleNode("wp:comment_author", manager).Value,
                                           AuthorEmail = commentsIterator.Current.SelectSingleNode("wp:comment_author_email", manager).Value,
                                           AuthorIP = commentsIterator.Current.SelectSingleNode("wp:comment_author_IP", manager).Value,
                                           PostedAt = DateTimeOffset.Parse(commentsIterator.Current.SelectSingleNode("wp:comment_date_gmt", manager).Value),
                                           AuthorUrl = commentsIterator.Current.SelectSingleNode("wp:comment_author_url", manager).Value,
                                           Content = commentsIterator.Current.SelectSingleNode("wp:comment_content", manager).Value,
                                       };

                    var commentType = commentsIterator.Current.SelectSingleNode("wp:comment_type", manager).Value;
                    if (!string.IsNullOrWhiteSpace(commentType)) comment.Type = commentType;

                    if (parent == 0)
                    {
                        comment.Id = int.Parse(commentsIterator.Current.SelectSingleNode("wp:comment_id", manager).Value);
                        comment.Replies = new List<WordPressPost.Comment>();
                        p.Comments.Add(comment);
                    }
                    else
                    {
                        foreach (var c in p.Comments)
                        {
                            if (c.Id == parent)
                            {
                                c.Replies.Add(comment);
                                break;
                            }
                        }
                    }

                }

                results.Add(p);
            }

            return results;
        }
    }
}

WordPressModel.cs

using System;
using System.Collections.Generic;
using System.Text;

namespace WordPressExportReader
{
    public class WordPressPost
    {
        public class Comment
        {
            public int Id { get; set; }
            public string AuthorName { get; set; }
            public string AuthorEmail { get; set; }
            public string AuthorUrl { get; set; }
            public string AuthorIP { get; set; }
            public string Content { get; set; }
            public string Type { get; set; }
            public DateTimeOffset PostedAt { get; set; }
            public List<Comment> Replies { get; set; }
        }

        public string Title { get; set; }
        public string Content { get; set; }
        public string Slug { get; set; }
        public string OriginalUrl { get; set; }
        public List<string> Tags { get; set; }

        public bool IsPage { get; set; }
        public bool IsDraft { get; set; }
        public DateTimeOffset PublishedAt { get; set; }

        public List<Comment> Comments = new List<Comment>();

        public override string ToString()
        {
            var sb = new StringBuilder();
            if (IsDraft) sb.Append("[!!Draft!!]");
            if (IsPage ) sb.Append("[Page]");
            sb.Append(' ');
            sb.Append(Slug);
            sb.Append(' ');
            sb.Append(Title);
            sb.Append(string.Format(" ({0} comments)", Comments.Count));
            return sb.ToString();
        }
    }
}