Erica Sadun of Tuaw had created a screenshot utility for the iPhone, however it was only for the technically inclined.
The good news for not so technically is that with iPhone firmware 2.0 its very simple to take screenshot as it has a built-in screen capture shortcut.
All you need to do is Hold the "home" button, then hit the "power/sleep" button, the screen will momentarily flash, and voila, the iPhone’s current screen contents will be saved to the Camera Roll.
