I just upgraded from a MBA rev A to a rev B. I experienced this with both machines, so it's not just a rev A issue... I use a Bluetooth Mighty Mouse and everything is fine... until my hourly wireless Time Machine backup starts. Then the mouse cursor becomes very choppy and sluggish. As soon as the hourly backup completes, the mouse's responsiveness returns to normal. Throughout all this, the trackpad is just as responsive as always -- no change there. I don't have another bluetooth mouse to see if its just the Mighty Mouse. When this happens, the Activity Monitor is not spiked. The fans aren't running loud (so I don't expect its an overheating issue). This doesn't happen during a large wireless download -- just Time Machine. It's not a big deal, but rather an annoyance. Any ideas why? Or even more to the point, any ideas on how to fix it?