AT&T has announced that MMS will finally be available to US iPhone owners on September 25th, the official news comes after a report that Apple could release iPhone OS 3.1 next week. Despite the announcement of MMS availability AT&T still has no news on tethering support only saying that it will be offered "in the future".
MMS will be enabled for iPhone 3G and 3GS owners on that day via a software update.
In the press release AT&T also makes mention that it is constantly striving to improve network capacity.