Since the launch of the iPhone 3G S, AT&T has been scrambling to appease the loyal Apple fan base.

AT&T came under fire for not immediately supporting tethering and MMS, new features in the 3G S, and for its upgrade pricing plans for existing customers.

The carrier did alter its cost structure to accommodate subscribers who upgraded, but the tethering and MMS support issues remain unresolved, leaving industry watchers to speculate on when AT&T will introduce the features and how much it will charge for them.

Most recently, the mobile app blog Appmodo reported that tethering and MMS would be out in September, rather than July. However, an AT&T spokesperson told InternetNews.com that MMS for the iPhone 3G S is due out by "late summer" and that no date has been set for tethering, though it will be available at some time in the future.

Meanwhile, Appmodo is reporting that tethering will cost iPhone 3G S owners an additional $55 a month, but AT&T denies that at its Facebook page. It states, "There are a lot of reports out there, but wanted you guys to know that rumors of $55 tethering plan on top of an unlimited data plan are false. We'll have more news to share when the iPhone tethering option is closer to launch."

As for MMS messages, the carrier said they will be included in current text messaging plans.

(photo courtesy of Appmodo)