I think it's a win for MS for many of the reasons that @Haacked lists on this blog post.
IMO MS is too much driven by profits and control to realize expanding the .NET OSS community will be a NET win for their .NET platform and surrounding tooling / aspirations.
IMO MS is too much driven by profits and control to realize expanding the .NET OSS community will be a NET win for their .NET platform and surrounding tooling / aspirations.