The Logitech MX900 optical bluetooth mouse is nice, but is unsupported on Mac OS X. It still works as a basic mouse, but the system prefs don't let you see the battery level, assign keys or anything like that. It seems to also have a rather jumpy cursor behavior. I plugged in a USB old-fashioned-rubber-ball mouse for comparison to the MX900. The USB mouse would track movement very accurately, keeping the pointer in a tight circle as I moved the mouse. When testing the MX900, however, the pointer would suddenly jump to another part of the screen, even though I was simply moving it in small circles as I was the USB mouse. This was driving me insane. I upgraded the bluetooth drivers in my powerbook. No fix. I threw the mouse across the room into the trashcan. Oddly, that didn't help either. I fished it out. I plugged its base into the Mac and paird the mouse with the base (still bluetooth, but not to the Mac). The Mac saw it as a USB mouse, then, and the jumpiness was quelled. So there must be an issue with the bluetooth in the Powerbook. Occasionally, I get odd key repeats and lag with my Apple bluetooth keyboard, as well. That's really annoying as well -- totally throws off my typing rhythm. I hope Apple fixes it soon.

** update: the MX900 is no more. I just couldn't take it.