Search and you shall find.
http://forum.ppcgeeks.com/showthread.php?t=5091 - FAQs
http://forum.ppcgeeks.com/showthread.php?t=4621 - Threaded SMS on the 6800
And it is Threaded SMS not MMS. It displays text messages as a chat conversation. I am locking this thread since it is not necessary, and please do not ask for the application. If you want to know why, just run a search and you'll find the answer.