There's a ton of mail going over the Mono mailing list. Lots of people offering to help, lots of discussion about different compiler design techniques, whether they can use the GPL/LGPL because of linking concerns, and so on.
Someone's even written a small part of the VM, enough to do Fibonacci calculations. They discovered that it's fast (although I suspect this has a lot to do with the fact that they didn't implement much of the VM) and that the Microsoft .NET implementation dumps core at fib(25). :-)
I'm getting lots of pointers to compiler, VM, and other
systems that I'm busily forwarding to people like Damian and Dan. Because, you know, they don't have enough to do already :-)
--Nat