Hyper-V RC has three main enhancements from the beta release:
<ul><li>An expanded list of tested and qualified guest operating systems including: Windows Server 2003 SP2, Novell SUSE Linux Enterprise Server 10 SP1, Windows Vista SP1, and Windows XP SP3.
</li>
<li>Host server and language support has been expanded to include the 64-bit (x64) versions of Windows Server 2008 Standard, Enterprise, and Datacenter - with English, partial German, and partial Japanese language options now available and the ability to enable the English version of Hyper-V on other locales.
</li>
<li>Improved performance & stability for scalability and throughput workloads.</li></ul>
Now a few screendumps:
Fedore Core 8:

What i particularly like very much, is the ability to keep 1 VM from taking all available CPU:

Power usage of the current hardware: 65-70W.
I will change the videocard to get some reduction on that, but also add some more drives and an extra NIC. So usage will get a bit higher by that.
Getting your physical machines virtual is not an easy job BTW, for as far as i can tell (the host is only 24 hours young). Nevertheless, i really like what i see so far.