Bobby Lashley is the next former WWE star to make his way into MMA.  He spoke with the Daily Star about it here:

Lashley has his sights set on MMA, and has been training hard, to avoid going in as a typical wrestler. He tells me his kickboxing and striking have come on leaps and bounds - "I want to knock people out on my feet and submit people" - and that he's looking at his debut as early as August, or even on PPV in October.
 
"I want to be an MMA guy who used to wrestle," he says, but he's not ruling out wrestling. Lashley's great mates Angle and Booker made the switch to TNA and have obviously been bending his ear to get him over there.

The only two companies doing PPV's in October are Affliction and UFC.  I could see UFC bringing him in to face Brock Lesnar, because the marketing potential is very obvious.  However, it is also clear that companies like Affliction looking for names to draw would be interested in paying him good money too.  It's also possible that Elite XC could try to run a PPV in October if the May debut goes well.  Kimbo v. Lashley, anyone?

That being said, companies like Affliction and Elite XC should be very wary of signing Lashley to a big contract for his name value.  He was never a draw at all in the pro wrestling world, and doesn't have anywhere close to the name value of a Brock Lesnar or Kurt Angle.  Without a hype machine like UFC behind his debut, Lashley is not going to draw very much.