The 3G iPhone's second most persistently rumored and desired feature (or not), GPS is built in for location service hotness, which Steve says is "gonna explode." Location data comes from a combo of cell towers, Wi-Fi and GPS. Google Maps is still the default interface. Wilson says that's it's probable Telenav will do an SDK app with more advanced GPS sorcery though. Updated with video, which shows live tracking, local search, live traffic info and turn-by-turn navigation.