What can cause an iPhone 4 to not actually sync data when told to sync? My iPhone 4 (iOS 6) has stopped syncing wirelessly (with my Mac) over the course of the past few weeks.  When I connect it via the cable, iPhoto pops up and I can get the photos off, but it doesn't start syncing the music / apps automatically.  I have to hit the "sync" button, and even then, it doesn't appear to be pulling the "last played" data off the phone.  

The checkbox for "Open iTunes when this iPhone is connected" is checked, as is "Sync this iPhone wirelessly", and the "Sync Music" stuff... I haven't done anything over there.  I've restarted the iPhone several times, did a restore after 6.0.1 came out, and am considering reinstalling iTunes on the Mac (though I'm not even sure that's easy or possible).

What might be stopping the sync from being effective?
iTunes uses iTunesHelper.app to detect if an iPhone has been plugged in. This app is usually started as a login item. Therefore you could check if iTunesHelper.app ist listed here: Preferences -> Users -> Login Items. If it's not listed you can drag it back as described here: https://discussions.apple.com/thread/2313998?start=0&amp;tstart=0.