two major announcements this week
Windows 2008 R2 and SCVVM 2008 R2 both have done RTM.
Windows 2008 R2 should be in partner hands mid July and SCVMM2008 R2 you can get right now on Microsoft Connect.
These are two major updates to updates to enable Hyper-V Live Migration in a clustered environment.
There are a number of other improvements but these are the main once I am looking at.