User blog:Argorrath/Black Ops II Nuketown Zombies in in-game store for Xbox

Although Activision and Treyarch haven't confirmed the release date for Nuketown Zombies for non-Season Pass holders, but it appears the map is available on the in-game Xbox LIVE store.

People who acquired the Season Pass and try to download Nuketown Zombies are getting plagued with errors.

With this in mind, Season Pass Holders will most likely obtain the map in January.

Source: http://www.charlieintel.com/2012/12/08/nuketown-zombies-appears-in-the-black-ops-2-in-game-store-for-xbox/