Thanks for all this precious information.
I was wondering about the impact of an update on an existing Virtual Server 2005 with VMs in production.
Any particular problem ?
Eric - I'm not aware of any problems and have had none myself in upgrading several environments to R2 code (and through many builds inbetween the public beta and RTM). Be sure to follow the upgrade instructions carefully though at http://blogs.technet.com/jhoward/archive/2005/11/14/414286.aspx, which are also documented more fully in the readme files with Virtual Server 2005 R2 once it becomes publicly available (not long to wait now!)
Keep a backup of the VHDs before you upgrade, just in case you need to roll-back, and make sure you have the time to schedule downtime during the upgrade.
Only other thing is to make sure you install the latest version of the VM Additions in guests - Virtual Server will log events that the additions are out of date until you correct that each time a guest is started up. This will also enable you to run Windows Server 2003 SP1 as a guest operating system without the performance hits (unless you already have the hotfix from KB900076).