Encouraging Co-Operation In MMO Titles?

Thanks to Skotos.net for their article discussing ways players can co-operate positively in massively multiplayer games. The piece starts by talking about socializers, those "...players who are there because they want to interact not just with the game system, but also with other people", and then specifically discusses those who "...try and develop their own hierarchy by latching onto something within your gameworld to use as a token of control" (such as using friend/enemy markings in The Sims Online?) The article concludes by talking about whether MMOs encourage out-of-the-box socializing not designed by the creators: "Is your system robust enough to allow players to freeform Spin the Bottle? How about Pictionary? How about Charades?"