This weekend, Treyarch has confirmed that double XP is on offer in all online matches within http://www.trueachievements.com/Call-of-Duty-Black-Ops-....htm
in anticipation of the "Apocalypse" DLC being unleashed on other platforms.
Furthermore, Xbox 360 gamers can enjoy a free trial of the "Uprising" DLC over this weekend too. The trial gives access to four standard maps, namely Magma, Encore, Vertigo, and Studio. In addition, zombie fans can take down a few undead individuals courtesy of the Alcatraz-inspired Mob of the Dead map.
It should be noted that the aforementioned "Apocalypse" DLC was available on the Xbox 360 first, thanks to its release last month