On its face, it seems odd to pay so much for true turn-by-turn navigation on the iPhone when there's a built-in mapping application, but I still often throw my TomTom GPS in my bag when I'm travelling to an unfamiliar city. I'll have to think long and hard about whether to shell out for this.<p>Incidentally, TomTom's IQ Routes (which replaces the drive-time estimates used in most map databases with actual values collected from customers' GPS units) makes a huge difference in the accuracy of routing estimates, especially in big cities around rush hour.