Apple and AT&T may use an 8GB iPhone 3GS as a 'secret weapon' against the launch of the Motorola Droid if a rumor proves accurate. Two separate sources of BGR's say the two iPhone partners are considering replacing the existing 8GB iPhone 3G with a 3GS variant, preserving the same capacity and $99 price. The move would undercut Verizon by offering the latest iPhone at the same price as the less ambitious Droid Eris.