.NET is going open source?

No, not exactly. Today, we are announcing the release of the source code for the .NET Framework libraries under the Microsoft Reference License (sometimes referred to as Ms-RL). This allows for the viewing of the source code by anyone who accepts the license agreement. This will also setup a nice feature in VS2008 where debugging can step into our framework code. Cool!

See more information on Scott Guthrie's blog (screen shots on VS2008 using this capability) as well as HanselMinutes (Scott has an interview with Shawn Burke). Channel9 has videos coming as well.