Windows 2008 Hyper-V is th next generation based server virtualization technology that makes the best use of your high end hardware by adding multiple server roles as separate virtual machine or in simple terms you will be running multiple operating systems in parallel on the same hardware, one of the biggest player in virtualization technology is VMWare followed by XEN.
At this point of time only SuSE Enterprise is officially supported by Hyper-V, but that does not mean Redhat, Fedora etc wont work, it is just a matter of time that the support for other operating systems is added because there are surely kernel enhancements that have to be done to run multiple VM's with the Hyper-V technology and Microsoft's pet Linux company is SuSE gives them a heads up for the Hyper-V support. There is supposed to be done a lot of emulation to the hardware interrupts which is will take more time to support other operating systems and with the recent
Microsoft said Hyper-V beta for Windows Server 2008 is feature complete. Included in the list of operating systems supported are Windows Server 2003 SP2, Novell SUSE Linux Enterprise Server 10 SP1, Windows Vista SP1 (x86), and Windows XP SP3 (x86).
So Microsoft's Hyper-V technology is not yet a disaster that companies cannot lookup to using and the support for other Linux operating systems is surely on the way.