Taken from http://coderj.net/asp-net-mvc-helper-for-creating-twitter-bootstrap-form-fields/ and put into a Gist (to show OP)

FormHelpers.cs

namespace MySweetApp
{
  using System;
  using System.Linq.Expressions;
  using System.Text;
  using System.Web;
  using System.Web.Mvc;
  using System.Web.Mvc.Html;

  public static class FormHelpers
  {
    public static HtmlString FormField(this HtmlHelper helper, Expression<Func> func)
    {
      var result = new StringBuilder();
      result.Append(@"<div>");
      result.Append(helper.LabelFor(func, new { @class = "control-label" }));
      result.Append(@"<div>");
      result.Append(helper.EditorFor(func));
      result.Append(@"</div></div>");
      return new HtmlString(result.ToString());
    }
  }
}