I don't normally traffic in rumors. However, I recently tripped over a minor rumor, which I believe is reliable and of some interest.
After Apple revealed that iPhone OS 3.0 would permit turn-by-turn directions in third-party apps (if third-parties "bring your own maps"), I speculated that TomTom and Garmin would likely get on this train right away. I've now received unofficial confirmation that TomTom is indeed preparing a version of its GPS turn-by-tun navigation app — for release soon after iPhone 3.0 OS is out.
TomTom expects (apparently with good reason) that the new iPhone OS will not go public until late in the summer, August or September. The plan is for TomTom to release their GPS app sometime soon afterward, likely in the fourth quarter. Initially, the app will not support subscription services, such as traffic updates. This support should arrive in a later update. TomTom's biggest immediate concern is how to protect their software from being hacked and thus accessed for free.
Recall that TomTom had pre-announced such an iPhone app prior to the arrival of the iPhone 3G. The program never made it to the App Store, however, due to unexpected prohibitions in Apple's iPhone SDK. With iPhone OS 3.0, Apple is ready to lift these restrictions, freeing up TomTom to release the navigation software.