Holy crap... it actually works! 3.1, iTunes 9, ATT family plan. I followed these instructions [link], then enabled MMS in Settings/Messaging, and then tried an MMS and failed. It only worked AFTER I disabled wi-fi. I'm not sure what that means, but it is what it is.
Sweet!
EDIT: And I forgot to mention, VVM does still work for me after updating to the carrier file in that link.
Sweet!
EDIT: And I forgot to mention, VVM does still work for me after updating to the carrier file in that link.