I was looking for this feature on the 3gs but still unsure where/how to activate the turn-by-turn. I did a do directions (current location to said location) and I still had to click the next button for forward through it. I did see the gps blue dot moving but nothing else. I am working at the moment or I would mess with it more but any guidance on using the turn by turn would be helpful. I am thinking I have to purchase a GPS app (tomtom for example) to get it to work. I would mess with it on my way home from work but I decided to ride my motorcycle in today.
Gokivo (a monthly subscription service) is out already in the App Store. G-Map East/West has been around for a long time now as well. By next week, we'll see Navigon (Europe was released today), and later this summer TomTom. Sygic is awaiting approval for their North America apps. And those are just the ones that are *confirmed*. I fully expect other services (like Telenav, Nav n Go) to appear as well.