A couple of weeks ago I suggested that developers interested in having their .NET software run in other platforms should avoid Microsoft's Managed Extensibility Framework (MEF) as it was not an open source library.
I had a chance to discuss with Glenn, Sam and Bob the benefits of using the MS-PL for this library first over twitter and then over email.
Representing .NET's loyal competitor, I did not think that we stood a chance of getting Microsoft to change the license, but I was pleasantly surprised. Glenn understood the value of open source, Sam wanted to do the right thing about this library and CodePlex and Bob argued that Mono already had Mono.Addins anyways.
Thanks to everyone at Microsoft that helped change the license!