I was surprised to read a post on Scott Guthrie's blog that the .NET Framework Libraries have been released for public!!! You can now debug code and enter directly to the .NET Framework code, that is so cool from Microsoft!!!
Can we call the Microsoft .NET Framework now, Microsoft Open Source .NET Framework :)
Have a look at this post by Scott: http://weblogs.asp.net/scottgu/archive/2007/10/03/releasing-the-source-code-for-the-net-framework-libraries.aspx
Hope this helps,