Treyarch have released a 40 second preview of the Zombies mode. The Preview shows an automated bus (likely a new form of transport) as well as what seems to be one of the Zombie maps (A run-down suburb) and the zombies themselves (toting some new appearances). It has yet to show whom the zombie killers will be.
The video may be seen here:
A new sound effect video, entitled "Death", has been released.