Call of Duty's zombie game modes have always been a multiplayer-only kind of deal, entirely divorced from the game's singleplayer campaigns. A product listing on Amazon, however, suggests that might be about to change.
As you can see above, the game's description includes the line "The inclusion of a Zombies in gameplay, both in as an option in multiplayer, and as a campaign option".
A campaign option? Wonder how that would work. Maybe it's a new game + kind of thing, and you can replay the game with regular bad guys replaced with zombies.
Or maybe by "campaign" they mean Spec Ops co-op missions.