Windows Server 2008 R2 Virtualization gets Dynamic Memory and RemoteFX
Windows Server 2008 R2 also got some great enhancements as well. RemoteFX is a new enhancement for Hyper-V, which willow the ability to run 3D applications within a Hyper-V VM. This allows the virtual desktop experience to get even closer to the look and feel of an actual desktop. IT provides a great multimedia experience through VDI.
The other big change to hyper-v that was made in Windows Server 2008 R2 will also get Dynamic Memory, which will allow you to adjust memory of a guest virtual machine on demand to maximize server hardware usage. Some really cool stuff!
Great Post here: Dynamic Memory Coming To Hyper-V
Full virtualization announcement here: http://www.microsoft.com/Presspass/press/2010/mar10/03-18DesktopVirtPR.mspx