Call of Duty: Black Ops 2 will be getting a brand new DLC package entitled "Uprising" on April 16, according to this source material provided by Joystiq.
The source shows promotional material for a new set of maps and new zombie content, allegedly obtained at a Best Buy by the friend of this Twitter user. The material shows four new maps for Black Ops 2, as well as something called "Mob of the Dead," which could either be a new zombie map, or a brand new mode for the zombie portion of the game.
The four new Uprising maps are entitled Vertigo, Magma, Encore, and Studio. It is hard to tell exactly what the themes for the new maps will be, given the source, but some details can be inferred. Vertigo has a helicopter landing pad pictured, so it is probably set on a large skyscraper-style building. Magma implies that players will be having gunfights near an active volcano. Studio and Encore look more generic, so we would have to wait until Activision confirms that this indeed is going to be the next DLC for the game before finding out what exactly will be going on on those maps. Mob of the Dead is also pretty vague-looking from the pictured artwork.
If this leak is indeed accurate, then it would follow the precedence set by the previous DLC pack for the game, the Revolution pack. That DLC pack also included four brand-new maps, as well as a new zombie mode and map to play.
The April 16 release would most likely apply to Xbox 360 owners only, as Microsoft has an exclusive deal with Call of Duty to obtain DLC for the Xbox 360 first. PlayStation 3 and PC owners will eventually get the DLC as well, usually around 30 days after the initial release of the content.