It's worth noting that there are popular Mono applications shipped with most distributions by default (Banshee, Beagle, F-Spot, and Tomboy are all C# apps running on Mono using GTK# for their UI). That would seem to indicate that Mono isn't univerally hated by the F/OSS community, either.
I actually tell the non-Windows guys to get Mono to run my software. Of course, I don't test it on Mono, so I don't care if it crashs on Mono. I personally don't care much. Being a fanboy meaning understanding MS. MS is not making a fuzz, why should I? As far as I see, MS is happy with Mono bring .Net to more platforms, which is ultimatly like what MS done with Silverlight. Best of all, MS didn't spend a dim on it.