Vidkun Quisling changed factions, too.

Massively reports that faction changes are coming to World of Warcraft.

I hope they’ll work this in as in-game content, but my suspicion is that it’s going to be a micropayment-based out-of-game system, which kinda stinks. One of my favorite things about EQ2 was the betrayer system, that lets you take your race/class combo to the opposing faction through a series of quests.

Edited to clarify: I think this is a great idea, irrespective of how it’s done. But it would be even swankier if it added content to the game itself instead of just being a convenience for players.