iPhone 4 has been confirmed by Apple during sessions in WWDC that it contain 512MB of RAM! This is twice the size of iPad and iPhone 3GS! The original iPhone and iPhone 3G had 128mb, iPhone 3GS and iPad 256MB, now iPhone 4 have 512mb! This is a great news for us, not only we can do multi-tasking on iPhone 4, we can also be worry-free that it will lag if we open up too many apps!
This information is leaked from the WWDC Session Video which is now downloadable free in iTunes U.
Apple has said that iMovie for iPhone will only run on iPhone 4, if that is the case, it seems quite conceivable that it actually need more rams than any of the older models can provide. This might also be the result why iOS 4’s multi-tasking will not be supported by iPhone 3G as there might not be enough ram to even do so. [MacRumors]