Hyper-V, Microsofts replacement for their great Virtual Server product has been released. Full 64 bit client / guest support and free on a Windows 2008 Server. Would be nice to get a Vista version but we’re not holding our breath.
Expect a host server reboot and a re-install of the Intergration Services on each guest followed with a reboot.
You can get the download from here. It will be on Windows Updates around the second week of July.
