Currently a free agent: Dave Rayner (he was tendered as a restricted free agent but will likely be unrestricted)
New to the team: None
Really the only storyline for the Detroit Lions' special teams deals with the situation at kicker. Jason Hanson has dealt with injuries the last couple years, and in 2010 he had his season ended prematurely due to an injury in the Jets game. Dave Rayner took over and performed very well for the Lions, leading to them tendering him an offer before the lockout began. Rayner will likely be an unrestricted free agent when the new league year begins, but Detroit wants to re-sign him as an insurance policy.
The problem with this is that Rayner could end up finding a job elsewhere and opt to leave Detroit. If Hanson is healthy, he is expected to take the starting job at kicker, so Rayner would end up being cut loose unless the Lions opted to keep two kickers on the roster. That seems unlikely, so unless it's clear Hanson won't be healthy going forward, the Lions might have a tough time keeping Rayner around.
Aside from the Rayner/Hanson situation, things are pretty much the same for the Lions' special teams. Nick Harris is back as the punter and Don Muhlbach is back as the long snapper. (Stefan Logan, who has already been covered in this series, is expected to be back as the returner.)
Need going forward?
f the Lions are unable to re-sign Rayner, they will likely bring in another kicker for training camp and the preseason even if Hanson is completely healthy. Typically they like to have two kickers on the roster until the first round of roster cuts happens. At that point they usually move forward with just Hanson, and I would expect that to be the case again this year if he's healthy.