There are reports from some of the iPhone developers using iPhone OS 3.1 beta that iPhone MMS feature has started working on AT&T network. Apple enabled the MMS feature for At&T users in iPhone OS 3.1 beta release but was buggy at the time.
One of the developers reports that sending and receiving multimedia messages is working for him since 9th of July and another reported that MMS feature worked in several major cities during a road trip on the 17th of July. But for majority of the users, MMS feature is still disabled by AT&T. It’s likely that AT&T is enabling it phone-by0phone basis.
A reader has shared a screenshot showing that his personal iPhone SMS plan was set to expire on the 17th. It’s possible that this was the point when AT&T switched his account over to MMS, although he doesn’t have the ability to test on 3.1.
If you’re on iPhone OS 3.1 and AT&T , go and give MMS a shot and don’t forget to share with us in comments if it works for you.