For example, when you buy an AppleTV, iTunes on the same network will detect that there is a new AppleTV that hasn't been synced. Then you synchronize a 5-digit code between them and off it goes syncing over the network.
I would love to see iPhones and iPads show up in the same way and not require a sync immediately. This would be right on track with the life-without-wires they were pushing with the MacBook Air.