http://www.sherdog.com is reporting that the rumoured matchup is Dennis Hallman vs Kauro Uno.
I seriously doubt BJ Penn will fight MMA yet since he stated in an interview in full contact fighter a few months back regarding possiably fighting in MMA:
"...after I get good in wrestling and some good standup. I want to be well rounded before I go in. I dont wont to be a pure jiu-itsu guy."