Reportedly Mass Effect 3's multiplayer mode will be getting a dose of downloadable content at some point in the future according to an anonymous user on Reddit.
IGN reports that the 'unknown pack' appeared on an xbox live 'test server' at some point recently and was downloaded by the anonymous poster. The pack may include such characters as a Geth Infiltrator, Batarian Soldier & Batarian Sentinel. If the leaked DLC screen is accurate this unannounced pack may include six characters.