i highly recommend getting a bluetooth mouse if your powerbook has a built-in bluetooth adapter.
if you travel around at all with your laptop, and you like using a real mouse instead of teh touchpad, having a bluetooth mouse is terrific.
you don't have to carry any sort of adapater for the wireless to talk to, you don't have any wire to get tangled, its great.
i have the microsoft bluetooth mouse and i have been quite happy with it. the battery life isn't terrific, but i do use rechargable batteries which are rarely as long lasting as regular batteries, and it is a bit annoying that there's no way to really turn off the mouse save for removing the batteries, so when it's bouncing around in my backpack its wasting teh batteries a bit.
anyway, rock on. enjoy your powerbook.
josh