After a bit of back and forth with Peter, we came up with a straightforward way of dealing with the fact that the Wacom driver needs a logical input device per input type, but the X server only generates an input device per hal device. The simplest solution turned out to be a hal callout that generates additional hal devices on demand, which also means we can add information to the fdi files to only add the appropriate device types. Ought to land in rawhide in the near future, at which point tablets should be basically working out of the box. Except that xsetwacom gets device name -> type mapping by attempting to parse xorg.conf. Pass the suicide.
Today's other accomplishment was spending long enough looking at Toshiba ACPI dumps to figure out how to enable hotkey reporting without needing to poll. Of course, I then found that the FreeBSD driver has done the same thing since 2004. Never mind. Patch has been posted to lkml and I've shoved it into rawhide, so that'll improve things for most Toshiba users. There's a few machines that have an entirely different BIOS and we don't know how the hotkeys there work at all, so life continues to be miserable for those of you that own them. Sorry.