The Release Candidate 1 (RC1) of Hyper-V is now available as a optional update on Windows Update. Optional updates are not installed automatically by default. To install the update open the Windows Update control panel and click “View available updates” under the “Install Updates” button. Then check the Update for Windows Server 2008 (KB950049) and click install.
If you don’t see the update listed there could be a few reasons: 1) You may find that you need to click the “Check for Updates” or “Check online for updates from Windows Update” 2) Depending on how busy the Windows Update servers are it may take a few days to get pushed out to every server. 3) If you have the HP Network Configuration Utility installed you should refer to KB950792.
For additional information about RC1 see the previous Hyper-V RC1 Release Available on Microsoft Download Center! post.
Enjoy and Happy Virtualizing! - Taylor Brown - Hyper-V Test Team