For American iPhone users, today is a pretty big day. AT&T customers should now have MMS (also commonly known as picture messaging) on their iPhones. Update your carrier settings by clicking on your phone in iTunes and going to “Check for Update.” Then, to make sure MMS has been enabled for you, go to Settings -> Messages. You should see an option to turn MMS on. Now, whenever you’re sending a text message, you’ll see a camera icon you can tap to attach a photo.
MMS finally arrives on the iPhone for AT&T customers