We are pleased to announce the first build of our Early Access Program of .NET Reflector 6!
.NET Reflector 6 comes with a Visual Studio Addin that lets you use Visual Studio's step-through-debugging on assemblies that you don't have the source code for.
Have a look at my blog post: http://www.simple-talk.com/community/blogs/alex/archive/2009/09/22/74919.aspx for more details.
This is still a very early build. We don't guarantee that it'll work, and it might break your visual studio configuration or project configuration. Make sure you have backups (or source control) for any projects you use this on.
Post your feedback, or if you come across any bugs, in this forum.