The Windows Server Hyper-V Management Pack for System Center Operations Manager 2007 is now available for download here:

http://www.microsoft.com/downloads/details.aspx?FamilyID=502e7a26-2fea-4052-89fd-8f75142de4f2

This management pack allows System Center Operations Manager to manage the health of Hyper-V and of virtual machines.

Cheers,
Ben