I had this same problem when upgrading from Feisty to Gusty on my Toshiba Protege M400. I edited my /etc/X11/xorg.conf and changed the lines
Option "Device" "/dev/wacom"
to
Option "Device" "/dev/input/wacom"
then restarted X. Both /dev/wacom and /dev/input/wacom are symlinks to /dev/ttyS0, so I'm not sure why this made a difference.
I had this same problem when upgrading from Feisty to Gusty on my Toshiba Protege M400. I edited my /etc/X11/xorg.conf and changed the lines
Option "Device" "/dev/wacom"
to
Option "Device" "/dev/input/wacom"
then restarted X. Both /dev/wacom and /dev/input/wacom are symlinks to /dev/ttyS0, so I'm not sure why this made a difference.