The [MMOG] segment accounts for a fraction of the about $7 billion in annual U.S. sales of PC and console games, despite hits like World of Warcraft, which is published by the games unit of Vivendi Universal SA, and Sony's EverQuest series. Massively multiplayer games generated $540 million in revenue in the U.S. last year, up from $430 million in 2004, according to Dallas research firm Parks Associates.

The market's long-term prospects "remain to be proven," said Michael Gartenberg, an analyst with New York-based Jupiter Research. "All anyone has proven is there are a certain amount of people interested in the medieval-type fantasy games."
Link