No, no mouse here. My wife has a BT mouse with her Powerbook, and I can't stand using it. It's much too heavy! A corded mouse would be a possibility, but with the iBook it would have to stretch all the way around the monitor, and that's actually too far for the standard apple mouse. So you need an extension cord. What a pain! Anyway, I do fine with the trackpad. I imagine if I was doing a lot of photoshop or something on the ibook I might consider a mouse. But for writing/surfing, it's not worth the bother.
Of course I use a mighty mouse with my iMac, though!