This is a very important point. The obvious strategy for Microsoft is to open up enough of the platform to allow it to proliferate, but keep enough of it closed to give their implementation the edge. If you were hesitant to invest efforts in the .NET platform before this announcement, and you depend on the high level APIs, you might have more reason to worry now.

And (imo) there's no telling which way a judge might rule. Eg see the email exchange betwen rms & Bruno Haible on why CLISP is under gpl: http://clisp.cvs.sourceforge.net/*checkout*/clisp/clisp/doc/...

"I say this based on discussions I had with our lawyer long ago. The issue first arose when NeXT proposed to distribute a modified GCC in two parts and let the user link them. Jobs asked me whether this was lawful. It seemed to me at the time that it was, following reasoning like what you are using; but since the result was very undesirable for free software, I said I would have to ask the lawyer.

What the lawyer said surprised me; he said that judges would consider such schemes to be "subterfuges" and would be very harsh toward them. He said a judge would ask whether it is "really" one program, rather than how it is labeled."

I think the point here is to protect end developers: if you want to be safe from future patent issues, they are making it easier to opt out of even installing any of .NET besides the ECMA core on your development systems, thus providing a decent guarantee that even if the rug gets pulled out from under Windows.Forms or ADO.NET, your app won't be impacted.

... because you know C# and the CLI are soooo useful without "ASP.NET, ADO.NET, Winforms and others"...

Well... At least those apps that don't touch the poisonous parts are safe. Until Microsoft changes its mind and breaks a promise.

Does that include LINQ?

Seems like this is a pretty critical thing to do.