Your xorg.conf looks OK with a couple caveats. You shouldn't need this line in the stylus section:
Don't know if that will make a difference though.
Option "SendCoreEvents" "true"
In Hardy in "ServerLayout" didn't we need something like the following?
I guess using your mouse and keyboard Identifiers. I can't remember. I suppose the Option "CorePointer" takes care of the mouse.
InputDevice "Mouse0" "CorePointer"
InputDevice "Keyboard0" "CoreKeyboard"
And when we set the xorg.conf up in Natty didn't you have an eraser?
Since wacdump shows the stylus is on the ttyS0 port that isn't the problem.
Xorg.0.log looks good. You are seeing a:
which is why I brought up the "ServerLayout" question. Otherwise the stylus seems to be set up correctly. So unless there is some conflict between the stylus and mouse as to which is the core pointer that should be good.
(WW) Configured Mouse: No Device specified, looking for one...
(II) Configured Mouse: Setting Device option to "/dev/input/mice"
So then the question is it the default linuxwacom 0.7.9-8? I don't remember there being a problem with it and serial tablets. USB tablets yes, since usb was just being introduced to the driver. But things that long ago are vague.