Learn how to sign your iPhone apps, and deploy them onto real iPhone and iPod Touch.
"In our previous article on getting started with iPhone development, you learnt how to use the iPhone SDK provided by Apple to develop your first iPhone application. For testing purposes, you used the iPhone Simulator, provided as part of the iPhone SDK. While the iPhone Simulator is a very handy tool that allows you to test your iPhone applications without needing a real device, nothing beats testing on a real device. This is especially true when you are ready to roll out your applications to the world - you must ensure that it works correctly on real devices. In addition, if your application requires accesses to hardware features on an iPhone/iPod Touch, such as the accelerometer and GPS, you need to test it on a real device - the iPhone Simulator is simply not adequate. iPod Touch devices for testing."