"Zombies have been such a hit with our community that we were committed to bringing brand new zombie experiences to Call of Duty: Black Ops," Treyarch's studio head, Mark Lamia, said in the announcement. "We've taken extra special care to retain the essential ingredients of our Zombie game, and have also crafted a nice surprise for the fans."
[Original] It looks like the popular Zombie mode from Treyarch's Call of Duty: World at War will be making a return in Call of Duty: Black Ops. The game's viral site GKNOVA6 has been updated to show footage of Nazi zombies as they appeared in CoD: WaW (via Joystiq).
Treyarch is being coy about the content, admitting that work has continued on the zombie mode following the release of World at War, but not yet confirming the feature for Black Ops.
Meanwhile, community manager Josh Olin tweeted "if Zombies have anything to do with our top-secret Co-Op mode, then it's a safe bet there will be a trailer for it eventually..." in response to a user asking for Treyarch to simply reveal the feature.
From all of this evidence, it's apparent that zombies will be making a return to Call of Duty: Black Ops in some form. Will they be Nazi zombies? How about Communist zombies? Will additional co-op modes be available, similar to Modern Warfare 2's Spec-Ops, or not? Time will tell.