Firstly thanks for such a brilliant piece of software.
G5 1.8G dual
It continued to work fine when I upgraded to OSX 10.5, from 10.3, after upgrading my keyspan driver.
On upgrading to 10.5.1, TabletMagic now fails to work for me, I just get 'Starting Daemon...' continuously. I've approached Keyspan too, as the issue may well be at their end, but I thought I'd mention it anyway.