Walter Mossberg of the Wall Stree Journal wrote up his first experience with a navigation system powered by a GPS enabled Nextel phone. The TeleNav service Mossberg used was mentioned by MobileTracker several days ago.
Overall, TeleNav's setup is simple and its directions are easy to read and understand. But it's too slow, and it doesn't always work, which is a big problem considering that this product is designed to keep people from getting lost. Putting navigation into a cellphone is a good idea, but this service needs improvement. For now, I cannot recommend TeleNav.