After a string of free DLC packs that mainly focused on
Mass Effect 3's surprisingly popular multiplayer the first premium DLC package, called
Mass Effect 3: Leviathan, will come out later this summer.
Leviathan adds to Shepard's story, but takes place before the ending - obviously. Apparently, the reapers have a traitor in their ranks and it is Shepard's job to find him and get him to fully commit to helping the unified galactic alliance stop the reapers.
We also have the first batch of screen shots for coming-sometime-in-the-future-but-no-one-knows-when Wii U version of
Mass Effect 3. There's also one shot in there from the upcoming
Mass Effect 3 Firefight pack.