ANNOUNCEMENT - 2007.10.03:

• Microsoft is releasing the source code for .NET Framework libraries under the Microsoft Reference License.  This license allows viewing of source code, but not modification or redistribution. The source code will be downloadable and viewable by anyone who accepts the license agreement. 
• Microsoft will introduce a capability in Visual Studio 2008 to allow .NET developers who are debugging applications, to debug not only into their own source code, but also into .NET Framework source code using Visual Studio. 
• This release falls under Microsoft’s Shared Source Initiative, which encompasses a spectrum of source code offerings, complementing the company’s other activities around sharing source code.  This is another example of Microsoft’s continued commitment to increasing transparency and addressing developer needs.

My thoughts:

This is truly a step in the right direction for Microsoft, and an especially good thing for the .NET developers community. When I work on the Java side I enjoy having access to all the source codes to the various editions (standard, enterprise, mobile, etc.). It provides us developers better insight into the behaviors of our code when needed, and in many cases, the source code provide really good code samples on how certain tasks can be accomplished.

Now this is Shared Source (not open-source), meaning we have access to the source code for reference purposes (and thus the "Reference License") but we cannot modify and rebuild the code. Of course, we still have the opportunity to contribute suggested changes to the source code (via the product feedback process), but for the majority of developers building solutions on top of the .NET Framework, being able to step through the source code and debug applications with full transparency can significantly improve productivity.

More information:

• Scott Guthrie’s blog
• Podcast with Director Shawn Burke
• Microsoft Reference License (MS-RL)