In a surprise announcement within Scott Guthrie’s blog, Microsoft has promised to make the source code of the .NET 3.5 Framework libraries available under the Microsoft Reference Licence – essentially a “look but don’t touch” licence. You won’t be able to make use of the source code in your own applications, but it will mean that you can determine exactly how a class implements a particular feature.
It is planned that the release will begin with the .NET Base Class Libraries, including ASP.NET, Windows Forms, ADO.NET, XML and WPF. Later LINQ and WCF among others will be added. The source code will include comments and will be available as a single download that can be viewed in any text editor. Debugging support will also be available within VS 2008. The debugger will be able to dynamically download the .NET Framework symbols and source code and you will be able to set breakpoints and single step inside the .NET Framework code.