From an interview with Final Fantasy XI producer Hiromichi Tanaka, an interesting point about the support for voice-chat in mmorpgs:

1UP: Will the 360 version support voice-chat? We sure hope not.

HT: No, it won’t. The reason being is that we track player abuse through the chat logs, and if we removed the necessity of the chat log, it would be impossible to take action against abusive players.