You are here because you have the following error, huh?
Well, it might be everything or nothing but remember: every time you get an error, fire up the famous "Console" and check it out there.
In my case it was:
11/17/12 12:56:22.024 AM iTunes: AMDeviceValidatePairing (thread 0x1134e3000): Could not load pairing record /var/db/lockdown//87sds709s8ds9d8s0d8s098d.plist
So, you have a missing file which most probably was not restored after your recently fresh OS reinstallation. Just restore it from TimeMachine or whatever backup you are using and that's it.
If you do not have your backup, you may probably solve the issue by deleting your device's backup from iTunes (Preferences -> Devices). I haven't tried but that should work too. I hope this helps you out!