As of 2AM PST I am very happy to be the first (I think) to announce Hyper-V RC1 is now available for public download via the Microsoft Download Center. I want to personally thank the great team of Testers, Developers and Program Mangers that make up the Hyper-V Team, there are several improvements in RC1 that they worked very hard on.
Windows Server 2008 x64 Hyper-V RC1 Update - KB950049
This is the Hyper-V RC1 package for Windows Server 2008 x64. This package must be installed on Hyper-V server’s (physical machines). It includes the Hyper-V Server components for Full and Core installs, the Hyper-V Integration Components for Server 2008 x64 (see note below for RC1 improvements over RC0) and the Hyper-V Management Components for Full Windows installs.
Note This package is permanent. Once installed, it cannot be uninstalled. So you can’t got back to RC0 or Beta after installing RC1.