That was a good eye. I could see zombies maybe being connected to single player, but a zombie mission in the actual campaign, I don't think so. Maybe they just used the map layout for zombies. :p
Yeah I agree with Travis, afterall, zombies on W@W were based on MP maps.
Nacht der Untoten - Airfield
Verrukt - Asylum
Shi No Numa - No direct correlation with MP maps but takes similarities from Makin and Knee Deep
Der Rise - Nightfire