Michael Greene: The documentation for volume activation 2.0 has been updated today for Server 2008.  You can find it here:

http://go.microsoft.com/fwlink/?LinkId=75674

Running KMS on Server 2008 is functionally very similar to running it on Vista RTM.  You leverage slmgr.vbs to bring the service online and then clients find the server based on the DNS srv record.  BTW, Server 2008 KMS can be run within a virtual environment.

If you want to know which volume license keys to use when activating new machines running Server 2008, see page 19 in the Planning Guide and the FAQ.  You only need to put one key in your KMS, and it will handle requests from both Vista and Server 2008.  There are separate keys, and unique keys based on which version of server you need to activate.  Before you get excited - this is much easier to understand than it might first seem.  Simply decide the "top" version of Server 2008 you might install and then use that MKS key to activate the service on a 2008 server.  All versions in groups below that version will also activate off that key.  The groups are simple...