Here's how I got MMS going for now. Hopeful Juicy or someone figures out how to utilize the HTC MMS App, I like the looks of it.
It is backwards but works! Install v1.2 of the cab in this thread:
http://forum.xda-developers.com/showthread.php?t=556614 reverts you back to WM SMS/MMS, so once you install that cab, you will have to install Arcsoft like you used to, then go to your Pictures, and select MAIL instead of Messaging like you used to, and then the option of Picture Mail SMS/MMS is there. choose that. I tested and it sends and receives.
Good Luck!