According to a recent screenshot (shown below) which has been making the rounds on Reddit, Mass Effect 3 may have some multiplayer DLC on the way.
As you can see, the DLC contains several new downloadable characters. Supposedly, the person who originally posted it on Facebook downloaded it from the developer server.
Currently, characters can be purchased in packs in the ME3 shop, but none of the above ones are included yet. If this turns out to be legitimate (and it certainly looks it in my opinion), it will be the third major leak for this title. Hopefully there will be a confirmation or denial from Bioware soon.