Here's a feature you'll like for capturing screenshots on your iPhone. You can use it to capture displayed error messages, images, or practically anything you see on your iPhone's screen.
Simply press the Home and Sleep/Wake buttons simultaneously and immediately release them. The screen will momentarily flash, and the iPhone's current screen contents will be saved to your Camera Roll.
Even more interesting is the fact that when the app or screen you are in supports the zoom feature you can simply zoom to the desired depth, then trigger a screen snapshot using the same buttons above. This is particularly handy if you want to get a close up of something in a photo, on a Web site, or on a jar of Vegemite.