The details for Virtual PC 2007 Beta are now on connect.microsoft.com.  At the time of posting, there are no files in the download section - I imagine they will be there soon.

Anyway, the official news on the site, Beta 2 now supports:

  • Hardware-assisted virtualization if you have it (enabled by default)
  • Vista as a host
  • Vista as a guest
  • 64-bit hosts (no guests though)

Keep you posted as I find out more.