Blizzard has joined in on the recent trademarking party, filing three new trademarks for the name Cataclysm. The trademarks could apply to any number of unannounced projects, including a possible World of WarCraft expansion.
As reported by BlizzPlanet, the new project potentially relates to the Sundering, an event that occurred 10,000 years before World of WarCraft. The name refers to the implosion of the Well of Eternity, which was destroyed when the Burning Legion attempted to enter Azeroth.
At the moment, Blizzard is working on two unannounced projects -- a "next-generation massively multiplayer game," and what is speculated to be a new IP.

More...