If you want to take screenshots of your iPhone you can use Xcode for that or the iPhone SDK. Easy!
Download and install the iPhone SDK (free!) and plug in your iPhone – you could then take a screenshot of your iPhone. Below you find instructions how to do that via Xcode.
(1) Open Xcode then click on Window – Organizer
(2) Connect your iPhone – which should appear now under “Devices” (left pane)
(3) Go to the tab Screenshots to take screenshots from your iPhone