It's getting closer....!
Get all the information from the Virtualisation Team Blog!
Important caveats to remember:
I'm sure that the VMM 2008 technology will be updated as soon as possible to allow interaction with RC1, as it was released when RC0 was around, and RC1 brings some quite significant changes, hence VMM 2008 will need an update. If you still need to test Hyper-V and VMM 2008, I'd stick with RC0 for now.