Hackers at the #iphone IRC channel who collectively managed to build the first unauthorised iPhone GUI application have released the source code for the program.
The program which displays "Hello World" and does nothing else was buildable with the community-built toolchain and UIKit. It can be downloaded here.
The code is interesting because Apple has refused to allow hackers to tinker with its code and develop anything that resembles a third party application.
This, coupled with the iPhone's current popularity, is proving interesting to hackers who have so far left Apple gear alone.