Three bits of news that I should mention although if you monitor the Virtual PC home page, you'll know all this already.

1. Virtual PC is FREE. This will carry forward into the next version. The change was made in July, following the lead set by virtual server. You could be forgiven for missing this as we didn't even put out a press release. 
   Why are we doing this ? To quote Ben Armstrong "Microsoft views vitalization as a tool.  Virtual PC is used for a number of reasons, but the primary reasons are for development and test scenarios and application compatibility.  We already provide Virtual PC as part of MSDN for development and test users, and given that all our other application compatibility tools are free - charging for Virtual PC did not make much sense." 
2. Virtual PC 2007 is in preparation, although we have not yet set a date for a beta you can read the first of the documentation
3. Software assurance customers who licenese Windows Vista Enterpise will be licensed for up to four instances of the OS (or downgrades of it) on the same computer. 

The Windows Vista Enterprise page hasn't caught up with this - there is no reference to the "4 instance license" and it still refers to Virtual PC express which I think is now dead. The Software assurance page only mentions enterprise edition so it's not clear if SA customers can get this with Ultimate edition. I'll try to find out ...