This is not new, but maybe helpful for newbies..
There is a new simple hack that allows iPhone 2G users to enable MMS on their iPhone.
Your iPhone has to be jailbroken to enable MMS. This is first done by a clever Russian boy.
iPhone 2G OS3.0 Jailbreaked with Cydia.
Uninstall “asBattery” only if you had installed previously.
Instructions to enable MMS on iPhone EDGE
Step 1 -go to Cydia and download the package ActivateMMS2G “available in the repository of iSpazio.
Step 2 – Restart the iPhone.
Step 3 – Next go to Settings > Messages and make sure MMS Messaging is ON. If it’s not, restart your iPhone one more time.
Step 4 – go to Settings > General > Network > Cellular Data Network, and add the MMS info for your carrier, either Celcom, Digi or U-Mobile. For Maxis users, the Carrier will be Maxis 4.0 where the settings is configured automatically, and as such the Cellular Data Network will not be showen.
Do not install ActivateMMS2G on Firmware 2.2.1 or you will see a black screen with the Apple logo and you will need to do a restoration. If you haven’t jailbreaked your iphone 2G with OS 3.0, do a search with keyword ‘RedSn0w’ and follow the instruction there.