I'm currently in Seattle attending TechReady which is Microsoft's internal technical readiness conference, kinda like Tech.Ed is for customers, except this is lots of internal only NDA stuff. This of course means that I can't talk about a lot of the stuff I see.
One thing I can talk about that I've just seen is some of the new functionality that has been announced for inclusion in SP1 for Windows Server 2008 R2 - RemoteFX (a VDI feature) and Dynamic Memory (a Hyper-V feature). You can read more on these at the following locations:
Windows Virtualization Team Blog
Windows Server Division WebLog
Dynamic Memory really adds another notch on the belt of Hyper-V for running a dynamic datacentre. I'm sure most people will see this as a 'feature compete' with memory overcommit in VMware, and it essentially is, but done in a way that seems to be less prone to causing perf or stability issues if memory overcommit is incorrectly tuned. Time will tell...