I've been following this (but not closely) as I actually like the .NET world quite a bit (not including VB) and hope to see MS succeed in this. At the moment Mono has been bought and internalized by MS but sadly, Mono is still has .NET is being supported on Linux. The plan is for a full port of the "real" .NET framework to make it over, but the Ximinan Mono code is what is handling it at the moment.
Getting C# and F# on Linux and other OSes would rock.
I've heard that Mono is working decently well these days, and MS is really trying hard to get it working well.