Well, that wasn't too long to wait was it?
Tablet users: you will likely want to approach Vista Beta 1 slowly, as this is primarily an infrastructure release for us and many of the user interface items (read: Tablet PC Input Panel, Journal, et al) are not in this release. We will be making an interim version of the Input Panel available for installation on Vista Beta 1, but I do not have final details on that just yet.
As with any other prerelease software, back up your system first and be prepared to restore from that backup.
Seattle PI link: http://seattlepi.nwsource.com/business/234165_msft27ww.html