I have an intuos3 (PTZ) working with Snow Leopard, the following link to the latest driver update released on march 15, 2010 solved the issue for me.
Here’s the actual description from Wacom regarding what this driver fixes:
Driver 6.1.5-2 for Mac OS X v. 10.6, 10.5 & 10.4 (Intel & PPC G4+)
Release Date: Mar. 15, 2010
Size: 17.3MB
Driver supporting Intuos4 WL, USB versions of all Intuos4 (PTK), Intuos3 (PTZ), Intuos2 (XD), Intuos (GD) and Graphire2 (ET-0405A) pen tablets and the Cintiq 21UX (2nd Gen.), 12WX, 20WSX, 21UX, 18SX, and 15X pen displays.
Save the file to your computer and then double-click on “Install Wacom Tablet” to launch the installer.
NOTE:
This driver fixes some issues with the Intuos4 WL.
This driver includes a bug fix for Maxon Cinema 4D.
For concurrent use with a consumer tablet from Wacom, install this driver as well as driver version 5.05 or later. These two drivers can be added or removed independently of each other.
I already tested it and it works.