Big news from my team today. Windows Server 2008 RC1 with Hyper-V Beta, the official name of what I've been previously referring to as Windows Server virtualization, has just gone live on Microsoft.com. The Beta has many improvements over the preview or CTP release - Jeff's got more information of the details on our team blog.
You can download a copy from http://www.microsoft.com/downloads/details.aspx?FamilyId=8F22F69E-D1AF-49F0-8236-2B742B354919&displaylang=en
More information on the presspass site http://www.microsoft.com/presspass/press/2007/dec07/12-13EarlyBetaPR.mspx
IMPORTANT: When you install, you should select English US only, otherwise you may see error 87 when the Virtual Machine Management Service (VMMS) starts. The only workaround in these instances is to start the installation again.
If you recall back to our Community Technology Preview (CTP) release a few months ago, you had to run a couple of packages before the role was present in Server Manager. This is no longer necessary - the Hyper-V role will be present automatically.
Finally, if you have Windows Server 2008 guests built in the CTP, you should move to freshly installed VMs with this build running as the guest. You'll notice now that you no longer have to install the Integration Components in a Windows Server 2008 guest - they will be installed automatically with the OS install.
Have fun and Happy Christmas.