The iPhone 4 might actually have much more to it than anyone thought.
The rumour that the iPhone 4 has 512MB of RAM has been confirmed. The iPhone 4’s predecessor (iPhone 3GS) as well as the iPad only had 256MB of RAM.
The increased amount of RAM explains why the iPhone 4’s performance has improved greatly and why some apps (such as the iMovie app) are available only on the iPhone 4. Also the increased amount of RAM might have something to do with Apple adding the multitasking function to the iPhone.