Being that TomTom showed off their turn by turn navigation system at WWDC, and being that AT&T has hardly mentioned their Navigator app in recent memory, it seems odd that AT&T would be the first to release a turn by turn navigation app.

They were, though, in a free app download today. Don’t let free fool you. The app will add a $10 charge to your AT&T bill.

The application was developed specifically for the iPhone 3GS but it will work with OS 3.0 on other iPhones. The app gives you turn-by-turn navigation, updates traffic information and will let you search by your location for the cheapest gas.

AT&T may have made a smart play here, giving them the early adopters. I’ll be interested to see whether other turn-by-turns run for a similar monthly fee.