Sent it off to mono-devel.
With it, monobal now runs perfectly on both Windows and Mono without any harmless but noisy exceptions being printed to the console. (My previous patch didn't make async reads/accepts be catchable from the calling thread.)
Update: 4:36 pm:
> It look okay? Yes. It's in CVS now. It would be nice if we get tests for these too. Thanks! -Gonzalo