Well it’s about friggin’ time, and here’s how to enable MMS on your iPhone 3G or 3GS (sorry first-gen iPhones):
Connect your iPhone to your computer.
Open iTunes and click on your iPhone in the devices list.
Click check for updates.
Install the new update.
When the install and syncing finishes, reboot your iPhone.
Tap on Messages. Your iPhone will now have a small camera icon next to the text field. Viola, You’re done!