It's already out but not in a polished form, however SwirlyMMS has their app working on the iPad (Jailbroken only) and promises to have a fully polished user interface done within the next few weeks.
You can watch a video here:
[ame=http://www.youtube.com/watch?v=Ctnh4Unrt6Y]YouTube - MMS on the iPad using SwirlyMMS![/ame]
You can read the full article here: SwirlyMMS Jailbreak App Pulls Off Native iPad 3G SMS & MMS Support? :: App Advice