We have released a bunch of updated documentation in the last week.
The first thing to look at is the Live Migration Network Configuration Guide. The really neat part of this is that it talks through all the supported / unsupported network configuration options. It also talks how to use the network QoS support built into Windows in order to safely share network connections in such a configuration (this is a neat option that I often use in my demo setups):
The next thing to look at is a new Virtual Hard Disk performance white paper that we have released that analyzes the performance characteristics of virtual hard disks in Windows Server 2008 R2 and contrasts it to Windows Server 2008. Lots of interesting technical detail in here: