That "someone" is, unsurprisingly, the NSA (and other foreign surveillance companies associated with it). Apparently, they've been monitoring chat and currency exchange activity in both World of Warcraft and Second Life due to a concern that terrorists could use certain features in the games to chat covertly and launder money.
The video below, produced by The New York Times, explains, "when you enter the realm of World of Warcraft, orcs and monsters are par for the course. But you probably aren't expecting to run into terrorists and spies. They're there, though - at least, the spies are."
Watch correspondents Mark Mazzetti and Justin Elliott (of ProPublica) discuss exactly why the NSA is so interested in monitoring MMOs - and why that fear is so patently ridiculous: