Apple has made efforts to hide some of the actual tech specs of the iPhone from consumers. "We've since heard that the upcoming iPhone 4's RAM has again been upgraded, and will bring it to a total of 512MB of RAM, twice as much as the 3GS and iPad (original iPhone and iPhone 3G contained 128MB, while iPhone 3GS boosted to 256MB, and the iPad contains 256MB of RAM).
The 512MB figure, however, does agree with Digitimes report that confirmed a 960x640 screen resolution, thinner display, and indeed 512MB of RAM. Apple had confirmed this 512MB figure during one of the WWDC sessions, and have now verified this. The session it was revealed in is now available (Session 147, Advanced Performance Optimization on iPhone OS, pt 2) for registered Apple developers," reports MacRumors.