I'm not sure it's MS fanboys who hate Mono so much as .net developers/managers who don't take it seriously. I like Mono, and don't think it's necessarily fatal that it doesn't always support all the latest .net libraries (plenty of Windows .net developers are still targeting older versions anyway); it also has unique capabilities of its own (I've also used some Mono assemblies in Windows projects) They should really consider making a serious effort to implement WPF now though, now that it's finally starting to gain traction.
"Yeah, it's kind of funny. I think Linux uses more .NET on the desktop then Windows does."
also ironically, before it was ported to Windows (but I can't get it to install on 7 for some reason ...) Tomboy was like the only Unix-exclusive app I really missed when running Windows