Taking a photograph of the iPhone 4 Retina Display was not enough. Here are 2 screenshots of the iPhone homescreen from an iPhone 4 and an iPhone 3GS running iOS 4. The iPhone 3GS screenshot (320×480) was resized to be as big as the iPhone 4 screenshot (640X960).
Click image to see the difference:
Photos were posted on this thread at the Mac Rumors Forums.
Arabic version of this post on SaudiMac Arabic Edition.