It's been a gap in the functionality of the GPS-enabled iPhone 3G for months, and one that was promised for the 3.0 software update (even though third parties have been trying to get it working for a while now): turn-by-turn navigation. Finally, the light at the end of the tunnel has been conclusively demonstrated not to be an oncoming train; it's the faint guiding glow from TomTom for iPhone, the first announced TBT navigation package for the 3.0 software (X-Road is already in the store for 2.1 devices).
There's no cost information yet (Engadget speculates 'pricey' so as not to cannibalize TomTom's hardware business), and the launch date is only noted as after the June 17th 3.0 software availability, but it certainly looks cool: a software app combined with a custom bracket & charging cable, hands-free calling and 'enhanced GPS performance' included. For iPhone owners who don't yet have in-car GPS, this could be a fantastic offering, if the price is right.
Video of the TomTom solution in the second half of the post. I already own a TomTom ONE, and just ponied up the $79 for a year of map updates... probably should have waited.