Following earlier claims that AT&T would enable U.S. iPhone 3G and 3GS users to have access to multimedia messaging (MMS) by late summer 2009, the company today announced that MMS support will launch on September 25, 2009, roughly one month after the official end of summer. “We know that iPhone users will embrace MMS,” AT&T said in a statement today. “The unique capabilities and high usage of the iPhone’s multimedia capabilities…