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.

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.