From a recent interview on the design team for C# 4.0 Anders said about the room they meet to discuss the C# design:
We have been meeting in this room for nine years, three times a week.
This seems to be one of the reasons C# has evolved so nicely.
Sadly there are no actual details on the interview about what is coming up on C# 4.0. We have to wait until the PDC to get an idea of what will be coming.
Luckily, Mono's C# compiler is already 3.0 compliant, and we are ready to start adding 4.0 features the moment they become public.