I think teaming should be part of the game, but not in a major way. It could be possible to add other players to your team, and there could then be a list down the side of the screen displaying their picture, health, where they are and what they\'re doing. That way, players could split up to explore a dungeon and help each other out if one of them is in trouble.
Edit: I\'ve just realised this is exactly what there is in Neverwinter nights. Still, it\'s a good idea, even if it\'s not mine.