[Update on 2007-05-21] Wacom has an official driver now that works for me and does not require the workaround.
See this blog entry for details: http://blogs.msdn.com/saveenr/archive/2007/03/08/new-wacom-driver-for-vista-available.aspx
After running Vista RTM bits on a clean machine, I installed my Wacom tablet and the most recent drivers for Vista.
The good
new Tablet PC features were available after install. These include pen flicks, handwriting recognition.
The bad
Using the tablet for dragging, selecting, resizing, etc. in graphics applications introduced wierd delays that made it very awkward to use with Visio, Photoshop, Audacity, etc.
A workaround
The temporary solution that I found on a WACOM web forum was to install a very specific version of the driver (not the latest one as of Jan 9 2007).
After installing my tablet worked perfectly (exactly as it did under Windows XP). However, I no longer had the Tablet PC features like Pen Flicks, etc.
Location of driver:
Note that some users have also found other older versions that do not exhibit the problem.
Discussion of this on the WACOM web forum:
Step-by-Step Installation instructions (use at your own risk, this is not a final, released driver from WACOM)