Now that the iPhone is capable of supporting turn-by-turn voice directions a whole slew of different companies are working on apps to take advantage of it. AT&T has made themselves one of the first by releasing the new AT&T Navigator App on the Apple App store. The app, developed by TeleNav, is free for download but costs $9.95/month to use.
This monthly fee covers regular automatic updates and real-time traffic notifications. AT&T intends to push their new app alongside iPhone sales at AT&T stores. It should do well among consumers that don't remember how ridiculously unreliable AT&T can be.
Ribbing on the iPhone carrier aside, there are a couple of neat extra features on the Navigator app. Using the app you can search for the lowest gas prices in your area, find WiFi hotspots, and sync up directions with your Mac or PC.
It should be noted that the app does not store maps locally. If you're out of wireless range, you're out of luck entirely. That's a definite issue, and one that pretty much makes Navigator useless for cross-country trips. If you don't leave the city, you'll be fine. If you like to wander off the beaten path though you'll probably be better served with TomTom, or a real map.