Google have announced in a press conference that they are developing Google Maps Navigation to be used with iPhones. Google Maps Navigation is a turn-by-turn satellite navigation system similar to those that are already found on standalone systems that can be installed in cars.
However, while those systems can cost a monthly rate, or at least an initial set up fee, Google currently offers Google Maps Navigation for free. They have been offering this system for several months in the USA and have recently begun offering it in the United Kingdom as well.
At the moment, Google Maps Navigation is only available for Android phones, however that will soon change as Google has stated that they plan to develop it for other smartphones, including the iPhone. This will probably encroach on the current market for GPS navigation technology, currently dominated by commercial satellite systems such as TomTom and Garmin.
The Google Maps Navigation system is allegedly as comprehensive as a traditional standalone GPS system, although it downloads the maps on demand, rather than storing them in the device. This means that the system requires an active connection, at least when planning routes, although the route is then cached for the duration of the trip.
Google has not said exactly when Google Maps Navigation will be available for smartphones, or even if they have currently reached an agreement with Apple.