I've just got a Wacom Pen & Touch tablet CTH670. I could not make it work straight away with Archlinux, but then found out that I had to follow the steps in this forum post , which was originally meant to be for the CTL-470/k.
In case the attachment in the linked forum post doesn't work, I am duplicating it here.
UPDATE: there seems to be a small issue with that version posted above. The version that works like a charm with my tablet is http://sourceforge.net/projects/linuxwacom/files/xf86-input-wacom/input-wacom/