In looking at the potential of the iPhone I am most excited by the idea of mixing digital versions of the world with that of the physical world. There is a neat article by Jonathan Fildes on BBC News: Mobile Phones Expose Human Habits. The article covers a range of data collection being done on human movement using their phones and mentions ideas put forward by the likes of Nokia for more deliberate integration of such things into future devices.
This crosses neatly into Augmented Reality, Mixed Reality and Ubiquitous Computing, all terms popular with computing and media theorists. Check reports like this one from the Metaverse Roadmap Project or go as far as those guys at a_rage.
Here is a prototype example using Googles Android software:
Enkin from Enkin on Vimeo.
And there is Nokia's (perhaps slightly cookie) version as well. I will come back to Android a little later - looks exciting.