TomTom's much-ballyhooed iPhone GPS app best step its game up, else it'll get left in the dust by none other than Navigon. The lesser-known nav company today introduced the second major update for its MobileNavigator iPhone app, and the feature additions aren't anything to scoff at. For starters, the program has become the first on-board navigation app for the iPhone to gain text-to-speech functionality, and just in case hearing street names belted out th
