Mono is going to be represented at Microsoft's PDC this year. Miguel de Icaza, who leads the open-source Mono effort, is going to present a session about Mono and .Net. If you search this blog for "mono", you'll see that I've been paying attention to these guys for quite a while now, and wondering the whole time why Microsoft isn't paying closer attention.
I'm really encouraged to see that Miguel and the Mono team are getting some exposure. I still believe there's a lot for both Mono and Microsoft to gain by strengthening this partnership. Microsoft needs to embrace Linux more than ever before, and frankly, Linux could really stand a little bit of leadership to help that platform coalesce.
Good luck, Miguel!