The hypervisor support in Server 2008 is now out in beta and it's great to see the product hitting the street. Virtualization is a huge change for the industry that can do a lot for everyone from data-centers to software houses, to people who just want to be able to run programs without worrying as much (yes, yes, escape exploits would remain a concern).
Here's a review from Windows IT Pro. Of course, this isn't what I actually work on - I work on the Virtual Machine Manager. Sadly, our product is still behind closed doors - I can't wait to get it out to customers.