Since Apple says a) jailbreaking may be illegal and b) the terms of the SDK prohibit "real time route guidance," it seems like it may be a long time before we see legal turn-by-turn on the iPhone. This week, though, there was some light at the end of the GPS tunnel.
At Mobile World Congress 2009 (MWC09) in Barcelona, Spain, Sygic is demoing a version of their namesake GPS navigation software running on an iPhone 3G. According to a post on The iPhone Blog, the Sygic software uses maps from TeleAtlas, the same company that supplies map data for Google Maps. Sygic produces similar software for Windows Mobile and Symbian devices.
From the screenshots in the post, the app appears to be similar to what many of us are used to with our TomTom, Garmin, and Magellan car navigation systems. Whether or not Sygic will be lucky enough to get this one into the App Store is unknown, but this app is definitely worth watching.
Thanks to Topper for the tip!