Earlier this week (June 26th), Blizzard Entertainment filed for three trademarks for the word Cataclysm for "Paper-based products, online games, and computer games." The domain wowcataclysm.com expired this year on June 26th and the site that controls this domain is none other than GoDaddy.com, who actually handles Blizzard Entertainment's domains.

There are two assumptions on what this could be:

1) This could be the name of Blizzard's up-and-coming unannounced MMO, whose name will be announced (and more) at BlizzCon, which starts on August 4th in Anaheim, California.

2) This could be the name of World of Warcraft's next expansion, which is rumored to be about the Maelstrom, a word that is relative to Cataclysm

An exempt from WoWWiki, an expert site on WoW Lore, says this about cataclysm, which may shed some truth on the latter assumption:

The Great Sundering, also known as simply the Sundering or the Cataclysm, was a world event which reshaped Azeroth approximately 10,000 years ago at the end of the War of the Ancients. This event was triggered due to the Well of Eternity being destroyed.

Prior to the Sundering, there was only one continent on Azeroth, referred to as Kalimdor. In the catastrophic explosion, eighty percent of the land mass was destroyed, leaving behind the major continents and scattered islands that are known today: Northrend, Kezan, the Eastern Kingdoms, and the remnant still referred to as Kalimdor.

The site of the Well of Eternity became a swirling vortex of power known as the Maelstrom

I personally hope that this is WoW's next expansion, what with all the work I've done on my Blood Elf Rogue and Night Elf Druid, but only time will tell.