It would be pretty cool if we could get a tweak for WiFi Sync that would allow us to sync wirelessly even though our iDevice isn't connected to a power source.
Is this possible to make?
Open up your iTunes and connect to your wifi. You should be able to press the button regardless of what that message says as long as you have previously set up wifi sync. Trust me. I do mine all the time. Just tried it to make sure, phone in my hands not plugged in and laptop in my living room. Syncs fine.