As I discovered from here and from a colleague, the previously only internal WMDC is now at beta 3 stage and available for review and download:

http://www.microsoft.com/windowsmobile/devicecenter.mspx

The device center was made available roughly at the same time as Windows Vista RC2 was quietly made available. Of interest RC2 is now smart enough to be BIOS aware; although prior installs worked without this change my work Laptop now requires a BIOS upgrade.