TeleNav announced that they will release a turn-by-tunr iPhone 3G GPS solution pretty soon. TeleNav is most known for their GPS navigation software for some other smartphones.
TeleNav confirmed that the iPhone 3G app will include full-color 3D moving maps and the turn-by-turn voice guidance and traffic-aware routing. No price or release date has been made public, but keep checking back and i’ll inform you of any updates.