I recently installed Ubuntu 6.10 on the Panasonic Toughbook CF-18 Tablet PC (model CF-18FDHZBVE) that I had previously installed Ubuntu 5.10 on (you can find that writeup here).
Read it here if you own one of those
This model comes in two versions – one with a touchscreen (i.e. you can use your finger) and one with an active digitizer (i.e. you need the pen). The digitizer model is the one in this article.