Comment 26 for bug 152187

Good news, I've identified the problem (for details, see http://article.gmane.org/gmane.linux.acpi.devel/26955 ) and submitted a patch to the linux acpi developers that appears to have a good chance of getting accepted. Updated ubuntu kernel packages are provided in this thread (thanks to Matthew Thomas for uploading them, this was more than my paltry internet connection could handle).

I encourage everyone to test them: the 2.6.22 package is for gutsy, the 2.6.24 package for hardy (caveat: wacom support is currently broken in hardy if you update to xorg-7.3).