So, Sun Microsystems open sourced Java.
Adobe open sourced Flex.

Now Microsoft is releasing the source of .NET. UPDATE: Krish points out that this isn’t open sourcing .NET, just releasing the source. That’s even lamer cause the other two have actually open sourced and are accepting submissions from the community.

Cool, but when you’re last to do something does it really matter anymore? This is a good move, though, and will help many of Microsoft’s developer community stay on Microsoft’s tools.