User blog comment:Magma-Man/Call of the Dead confirmed! Escalation Trailer Out!/@comment-3426464-20110421202214/@comment-1854594-20110422022601

I think they aren't showing anything from the zombie maps because they're being secretive. They don't have to make the incredible trailers like before because everyone knows about it by now anyway. They want to make sure once you get the map you have no idea what to expect at first so the players can figure it all out by themselves.