For those that don't know already: the first screenshots from the as yet unnamed DLC have been released via twitter. The first from Casey Hudson
shows what looks like a casino area in one of the Citadel's wards and what looks like Wrex talking with a human male in Alliance fatigues. Possibly maleShep, or Kaiden. The second shot from Mike Gamble
features a Krogan in what looks like a new armour design, wielding the mother of all sledgehammers on what appears to be Thessia. Indeed, I'm pretty sure the shot was taken on the MP Firebase Goddess map.
So, dose this mean the new SP DLC will take place on both Thessia and the Citadel, or that there will also be more MP DLC in addition to the SP? Time will tell.