I'm pretty sure Microsoft themselves having contributed to mono projects would invalidate any such lawsuit. Also, Microsoft submitted the whole common language infrastructure (CLI), the core of .NET, to ECMA as an open standard.
So, unlike most things Adobe and Apple, Microsoft has actually made the .NET infrastructure open, but you don't see people decrying people for wasting their development efforts there.
So if that's a perfectly fair question, the FOSS world should immediately start reviewing pretty much all efforts not currently centered around POSIX, OGG and Theora as possibly wasted.
"I'm pretty sure Microsoft themselves having contributed to mono projects would invalidate any such lawsuit"
No. It wouldn't. And, most of all, it has no effect on where they take .NET in the future. If they decide to break Mono by moving the reference platform and to make Mono developers run in circles, they can. If they decide to sue _users_ of Mono programs, they pretty much can, unless at least a significant part of the code being used is licensed in a patent-litigation-proof license, which, I gather, is not the case.
The whole case is that you just have to trust Microsoft to, for the first time in its history, act in a civilized way. You may judge it's an acceptable risk for you and your users, but I just don't think that way.
If they decide to sue _users_ of Mono programs, they pretty much can
Now you are pretty much talking bullshit. If this is actually somehow allowed in the US, that is a failure in the US justice system and for the remaining 95% of the world unrelated to actual reality. With all this time spent trying to avoid lawsuits, I sometimes wonder how people in the US manage to be productive at all.
Anyway, your arguments seems to boil down to that any platform which isn't under 100% open source control is a risky investment and that it's not worth it. If that is your point of view, I can respect that, but at the same time you have to accept that puts you in a very narrow window with regard to what markets and platforms you can develop for.
To me, from my point of view, that's just too deep into Stallman-land and not a viable strategy in the real world.
"that any platform which isn't under 100% open source control is a risky investment"
No. Not at all. I have invested a lot in AIX, DB2, Oracle and Solaris over the years. It's just that handing the reference to what your product should be compatible with to Microsoft and then trying to compete against them in one of their cash-cows is pretty much the ultimate stupid thing one could try.
Microsoft has been caught more than once in unethical and illegal activities, so, why take the risk? Are the APIs so far superior than anything else around? Is it working? Is it bringing a meaningful flow of new cross-platform software? Are the languages so wonderful nothing else comes close?
And yes: the US patent system is deeply flawed. And so is he justice system that allowed MS to abuse its monopoly numerous times. I can only hope both get fixed because the US is too an important market to ignore. It seems the EU has a good grip on the situation and maybe the US can follow its leadership on this.
So, unlike most things Adobe and Apple, Microsoft has actually made the .NET infrastructure open, but you don't see people decrying people for wasting their development efforts there.
So if that's a perfectly fair question, the FOSS world should immediately start reviewing pretty much all efforts not currently centered around POSIX, OGG and Theora as possibly wasted.