It has been announced at MMS conference during Bob Muglia his keynote System Center Virtual Machine Manager 2008 Beta is publicly available at the connect site.
System Center Virtual Machine Manager 2008 enables customers to configure and deploy new virtual machines and to centrally manage their virtualized infrastructure, whether running on Windows Server 2008 Hyper-V, Microsoft Virtual Server 2005 R2 or VMware ESX Server. When used in conjunction with the broad System Center management suite, customers can use SCVMM 2008 to effectively manage both their virtualized and physical servers and applications.
Some of the key features of SCVMM 2008 are:
You can download the beta from: http://connect.microsoft.com/