I first blogged on this back in January but based on all my meetings in Feb, very few ISVs seem to know about it.

Lets expand a little. The most often repeated reason I’ve been given for wanting access to the Microsoft source code is for debugging and optimisation purposes:

• A developer has a problem with their application and needs to see what is going on in the framework
• A developer wishes to understand what is happening when they call the framework  and how to make the most efficient use of it.

We have therefore made .NET Framework source available and we have simplified the setup a developer needs to do in order to debug into the framework with Visual Studio 2008 Standard and above.

This is good, I mean really good. 

Useful stuff:

• .NET Framework Library Source Code now available
• How to configure Visual Studio 2008 to debug .NET Framework source
• Support forum for developers using the .NET Framework source server
• Microsoft Reference License (in summary, it means you can read the source and debug with it, but not alter it or use it to build your own versions, sell it etc)