Unlimited canvas is very cool feature. But one function that I still feel too clumsy is panning around the sketch. When making a sketch even clicking the pan mode -icon feels too much - .

What information data does the n900 touchscreen provide? Position, pressure and the press-area size? f it provides the area size, it would be possible to do the pannin like this:
1 small size, propably fingernail or stylys -> draw
2 big size, probably fingertip -> pan

ie. panning with finger, drawing with sharp edge (you really cant draw with finger anyways)

The panning could also be done with fake multitouch: when you are pressing with one finger and then press in other place at the same time, the pressing point is interperated in between. So: if the jump of the pressure point is unrealisticly big, start panning mode.
-> panning with two fingers