If you have happened to play a little Zombies on Call of Duty: Black Ops lately you may have noticed that the new Moon Perk-A-Cola Machine - Mule Kick (which let's a player wield three weapons instead of two) is now available to purchase in Every Map
- including Nacht Der Untoten!
Here's Treyarch's official word on it.
After receiving positive reports from our Moon team regarding the new Mule Kick, we've decided to start manufacturing the drink here on Earth.
Starting now on Xbox 360, Mule Kick is available for purchase in every Zombies map, in addition to the other Perk-A-Colas. For the uninitiated, Mule Kick allows you to hold three weapons at a time for a truly aggressive and varied attack.
Source - callofduty.com/intel/511?path=...