Zip utility using System.IO.Packaging (.Net 3.0)

Program.cs

using System;
using System.Diagnostics;
using System.IO;
using System.IO.Packaging;

namespace ZipZip
{
    class Program
    {
        static void Main(string[] args)
        {
            PackageFile.CreateFromDirectory(@"d:\testzip", @"d:\test.zip");
        }
    }

    public class PackageFile
    {
        public static void CreateFromDirectory(string folderPath, string zipPath)
        {
            Debug.Assert(Path.IsPathRooted(folderPath));
            Debug.Assert(Path.IsPathRooted(zipPath));

            using (Package pkg = Package.Open(zipPath, FileMode.CreateNew))
            {
                string[] filesPaths = Directory.GetFiles(folderPath, "*", SearchOption.AllDirectories);

                foreach (string filePath in filesPaths)
                {
                    string relativePath = Path.Combine(Path.GetDirectoryName(filePath).Replace(folderPath, "."),
                        Path.GetFileName(filePath));
                    Uri uri = PackUriHelper.CreatePartUri(new Uri(relativePath, UriKind.Relative));
                    
                    PackagePart packagePartDocument = pkg.CreatePart(uri, System.Net.Mime.MediaTypeNames.Text.Xml, CompressionOption.Normal);

                    using (var fileStream = new FileStream(filePath, FileMode.Open, FileAccess.Read))
                    {
                        CopyStream(fileStream, packagePartDocument.GetStream());
                    }
                }
            }
        }

        private static void CopyStream(Stream source, Stream target)
        {
            const int bufSize = 0x1000;
            var buf = new byte[bufSize];
            int bytesRead = 0;
            while ((bytesRead = source.Read(buf, 0, bufSize)) > 0)
                target.Write(buf, 0, bytesRead);
        }
    }
}