Mojo is now easily obtained by doing a /kiss emote to an NPC outside of the Zul'Aman instance. Perhaps this was a hidden Easter egg all along, or this might possibly be a bug that's destined to be fixed in a future patch. So my advice to you serious collectors is to get this pet while the getting's good!
UPDATE: It appears as though the free and easy Mojos were, in fact, a bug. Furthermore, the bug has been hotfixed, restoring Mojo's rarity and uniqueness. Nethera, well-known WoW community moderator, confirmed that everyone who received a Mojo as a result of this bug will be able to keep him. (That makes me very happy, but I weep for all of those who missed the boat.)
Get Mojo, <strike>Free and Easy</strike>
January 27, 2008