So after more than a year of faithful service, my MX900 failed, so I bought a new mouse -- The Microsoft Intellimouse Explorer for Bluetooth (not "with" bluetooth, but "for" bluetooth). The transition is now, more or less, over. Here's what's what, for the sake of future generations: The IntelliMouse has a nice, velvety feel to it's skin, and features two thumb buttons, three finger buttons (including that center wheel, open-in-new-Safari-tab button), scrolling (of course) and sideways scrolling, achieved by tilting said scroll wheel back and forth. The sideways scrolling is slow, just like holding the right arrow key. No "scroll faster by pressing harder" or anything, so I doubt I'll ever use it. The Logitech MX900 has two thumb buttons, three finger buttons, PLUS, three more smaller buttons, also used by the fingers. Exposé is able to address all of these, and I had it set to show desktop when clicking the top small button and app/all windows on the thumb buttons. Microsoft IntelliMouse for Bluetooth: PROS: - nice feel. - long battery life, non-rechargable (unless you put your own rechargies in there). Unlike the MX900, it shuts off after like 10 minutes of being still, and i get the "Connection Lost" notification on the computer. It wakes up with about 1 or 2 seconds of shaking. - sideways scrolling. - Very small, size-of-my-thumb Bluetooth adapter. CONS: - Less buttons - less comfortable (but probably because my hand expects the MX900) - Stupid CamelCase comercialized name. "IntelliMouse" Logitech MX900: PROS: - Lots of buttons, all are mac compatible out of the box. - Smoother movement on my desk, but probably worn out. I don't use a mousepad. - The center wheel "click" is much more reliable. IntelliMouse I have to click fairly deliberately to actually make a Click event. CONS: - Crappy battery life. like 2 days - Cumbersome and quite ugly charging cradle/bluetooth adapter. 4 feet of powerchord plugs into another 4 feet of USB cable (which I don't use, since I have built in bluetooth on my powerbook) left me with lots of cable to work with every time i move locations. - Another silly name. M probably means "Maxiumum" and X means "Extreme". OK, well, whatever. Both mouses have no "OFF" button, and when I pack up, i have to remove the batteries. What have you all found? Pros or Cons?