Microsoft has released a finalised version of Hyper-V, its virtualisation technology that previously shipped on Server 2008. Microsoft claims it can beat off the competition (VMWare in particular) because it says it has a better offering in terms of price, packaging, depth, reach, control/integration and installed base.
Here is the full release, including a download:
http://www.microsoft.com/windowsserver2008/en/us/virtualization-consolidation.aspx