If you're looking to create awesome screenshots of your iPhone, you have a few options. You can either fire up something like Photoshop, or you can use a tool like Screentaker, which allows you to encapsulate your screenshots in an iPhone, or iPad frame.
Screenshots mated with the device from which they were taken, portrays a much more professional look in my opinion, and you'd be hard pressed to find an easier way to do this, than with PreviewMaker...