At the Microsoft Management Summit in Vegas, Bob Muglia announced the beta of System Center Virtual Machine Manager 2008, yes this is the one that can manage Hyper-V hosts!
It should be available on connect, though I can't connect to connect right now.
Microsoft has announced the formal name and beta availability of System Center Virtual Machine Manager 2008, a member of the System Center suite of server management products. The announcements came April 29 at the Microsoft Management Summit in Las Vegas, which showcased the beta of the System Center Virtual Machine Manager 2008 (VMM), managing both Hyper-V and VMware virtual infrastructure. Additional functionality new to this version of VMM includes Performance and Resource Optimization (Pro), which dynamically tunes virtual infrastructure, simplified virtual host cluster support, and other improvements and enhancements.
Microsoft, System Center, VMM, Virtual Machine Manager, Beta, Release