Blizzard's epic World of Warcraft expansion, Cataclysm, has sold 4.7M units since its release. The expansion went on sale worldwide on December 7. In the first 24 hours of release, it had sold 3.3 million units.

Blizzard boss, Mike Morhaime boasted, "We created thousands of new quests, introduced new lands to explore, and extensively revamped the game world for World of Warcraft: Cataclysm, making it our biggest and most ambitious expansion yet. We’ve been floored by the community’s response so far, and we’d like to thank them for their continued passion and support for World of Warcraft, and for helping Cataclysm reach this incredible milestone."

You can read more at Strategy Informer.