There are a few new navigation apps available trough App Store. It seems as if now was the time of "speedometer applications". There are three applications available, Speed, SpeedBox and Speedometer. They just display your speed (which is calculated by means of two positions and time difference because the API doesn't have the bearing- and speed features yet), that's all.
I wonder why not any of those feature average or top speed display or mileage or whatever. But I think we'll see this in a future update.
Furthermore, there is a new compass, similar to G-Spot, but looking nicer and also featuring all the common data fields you might know from your GPS receiver (like altitude, odometer, max speed and so on...). This pushes the iPhone a step closer to common GPS receivers like those from Garmin.
Unfortunately, there still is no sign of turn-by-turn...