Currently a free agent: Kevin Smith (he is a restricted free agent, but the Lions didn't tender him a contract offer)
New to the team: Mikel Leshoure (he was picked by the Lions in the second round of the 2011 NFL Draft)
Last year, the Detroit Lions kept four running backs when they established their 53-man roster: Jahvid Best, Maurice Morris, Aaron Brown and Kevin Smith. Smith, who is set to become a restricted free agent, has already essentially been told he won't be back next season. The Lions didn't tender a contract offer to him earlier in the offseason before the NFL lockout began, meaning he will be free to sign anywhere he wants.
Out of the other three running backs that were on the roster last season, only Best is a lock to make the team next season. He will be joined by draft pick Mikel Leshoure to form the Lions' one-two punch at running back. With Smith gone both Morris and Brown could end up making the roster, but neither has lock status. Morris is certainly likely to be on the team considering he showed some promise in the second half of last season, but Brown could be on his way out.
The other running back currently in the mix is former Boise State Bronco Ian Johnson. He joined the Lions' practice squad in November, and while he doesn't project to be an impact player, he could potentially work his way onto the roster and push Brown out of a spot if he has a good training camp.
Need going forward?
The Lions could sign a free agent running back to add another body during training camp, but that's the only movement I really expect with this position. If a veteran running back hit the open market I could see the Lions giving him a look just for depth purposes, but it's clear this position is going to sink or swim with Best and Leshoure in 2011.