It seems like a german website http://help.benm.at/help.php has the ability to enable both Tethering and MMS on AT&T (and other carriers) right this second (as opposed to AT&T’s “later this summer” promise for MMS and no promises for Tethering).
Of course you’ll need the 3.0 firmware (slated for release sometime today, trends and rumors seem to be saying 10 AM PST).
Anyways have fun once you can 