If iTunes isn’t seeing the update, odds are it isn’t available yet. You can click the Check for Update button under the Summary tab in iTunes while your iPhone is connected to keep checking for the update.
Once the update is available and installed, you’ll be able to start sending pictures in your text messages without even having to restart your iPhone first. AT&T said that iPhone owners won’t have to pay extra for MMS service — it’s included in the SMS packages we’re already paying for.
The downside to MMS is that first generation iPhone owners can’t take advantage of the feature. According to Apple and AT&T, only iPhone 3G and iPhone 3GS users can join in on the fun.