Plugging it in "just worked", but only as touchpad. (Relative movement, not absolute position.) I followed the instructions on the Ubuntu project page about editing my X configuration, and that got things working right. I haven't yet figured out how to assign buttons.
It's definitely easier than writing/drawing with a mouse, but not as easy as I'd expected--- there is still some learning curve. Using the GIMP worked better than Vyew.com's whiteboard, but unfortunately the latter is what I want to use it with. Vyew had rather horrendous lag, so that I was writing a second or so ahead of the lines showing up.