If you’re into that whole unapproved 3rd party iPhone thing, you should open Installer and install RiPDev’s Apple Screenshot Enabler. It does what it says and the method of taking screenshots is genius. When you’re on the screen you want to capture just hold down the Home button and toggle the Mute switch in either direction once. The picture is an uncompressed TIFF and sent to your Camera Roll. NICE! I tried other screencapture utilities and they’d capture the whole screen except for a several pixel-wide column on the right side. This Apple method gets the whole thing.
I should also add that you have to add the RiPdev source in Installer before it shows up in the listing: