The 3G iPhone's second most persistently rumoured and desired feature (or not), GPS is built in for location service hotness, which Steve says "gonna explode." Location data comes from a combo of cell towers, Wi-Fi and GPS, with live tracking. Looks like Google Maps is still the default interface. Two unspokens: What's it do to that otherwise nice battery life? And where's a carmount? I wonder if those GPS makers are in fact shitting themselves right now.