Kubuntu just shipped an update to their Linux kernel to 2.6.27-9. It didn't help about the U100 webcam problem but at the same time disabled the driver I had hacked up earlier. To make my life easier I extracted the uvc video driver from the kernel sources into a standalone package. This way I can recompile the driver with a simple make whenever a new update comes along.
I figure it could by useful for others as well, so it's up here for download. Compiling and installing should be fairly straight forward, just unpack the sources and type make in the extracted directory. For Intrepid you'll probably need to install a number of packages with essential build tools and at least the kernel header files. There are some HowTo's about compiling kernel modules without installing the full kernel source, however I think it should be enough to just
apt-get install build-essential linux-headers
Once compiled, just install the module as follows:
# cp uvcvideo.ko /lib/modules/$(uname -r)/updates
# depmod -a
This should be all. You can now test the webcam driver with for example xawtv. If you don't succeed, it may be that the old driver module is still loaded. Remove it with rmmod, or if you're entirely lost by now, just reboot.