Well, it does seem Microsoft was involved in buying some of the IP: http://www.zdnet.com/blog/microsoft/whats-microsofts-role-in...

But notice they don't say what that IP was, so it's not clear if it was Mono-related or not yet. Not sure what MS would do with any Mono-related IP or if they'd really care about it (except for killing it, of course, and I wouldn't think that is their intention).