I recently updated iTunes to the 9.2 version. My iPhone 3GS would sync with no problem. The first time I went to sync my 160GB iPod Classic, iTunes hung and I got the pinwheel of death. I restarted my Mac and rebooted my iPod, but still had the same problem.

The fix: Wait it out.

Just leave your iPod connected to the Mac. In anywhere from 5 to 20 minutes it will eventually start syncing. The harddrive on the iPod was definitely spinning during that time, so I’m going to guess that iTunes was optimizing the file structure or some such nonsense, but failed to put a user-facing messaging indicating as such into iTunes.