TomTom has released a $99 app that could enable Apple iPhone owners to ditch their standalone GPS units.

Originally announced in June, the TomTom app provides most of the features one expects from a standalone personal navigation device, including audible turn-by-turn directions and local points of interest. The navigation program uses a technology called IQ Routes, which TomTom said calculates the fastest routes to take.

The iPhone app also comes with full maps of the United States and Canada, and users can purchase maps of Australia, New Zealand, and Europe. The TomTom program is available now in the App Store.

The application is made possible by new application programming interfaces in the 3.0 software, as Apple gave developers more than 1,000 new hooks into the iPhone. TomTom will also be releasing a car kit later this year which enables users to attach their iPhone to the car's dashboard. The kit also takes advantage of new APIs in the 3.0 firmware, and TomTom did not say how much the accessory would cost.

Before the 3.0 software, turn-by-turn navigation was a pretty big hole in the iPhone platform because rivals like BlackBerry, Windows Mobile, and Symbian could provide this service. The latest firmware means iPhone users can expect to see multiple navigation programs in the App Store, as AT&T, Navigon, and Gokivo have also released turn-by-turn apps for Apple's mobile platform.

These moves have the potential to eat into the market share of standalone personal navigation devices, as consumers are leaning toward the convenience of a single device for all their mobile needs. GPS maker Garmin saw this writing on the wall a few years ago and it decided to jump into the smartphone game. While its first handset has yet to be released, the company has teamed with Asus to release a slate of handsets that have deep integration with location-centric services.

Registration is now open for the leading enterprise communications event, VoiceCon. It happens in San Francisco, Nov. 2-5. Find out more and register.