I've had my black iPod nano since Christmas, and it has always worked fine on my PowerBook. I recently got a 17" MacBook Pro Core 2 Duo and plugged in my iPod, and it doesn't show up on the desktop or in iTunes. The iPod screen shows the battery is charging, but that's it. Checking in /Volumes, iPod isn't mounted there either. I didn't have library sync turned on, so I can't imagine what the problem would be?