If someone is in a Lobby waiting for a game to start, and there is room, it should allow you to Join Friend from the dashboard flyout. Being as busy as it is, every game I have played has filled instantly. It does have parties though like Halo, so at least you can stay together for an evening of gaming.

Game of the Year... possibly, but Assassin's Creed is out next Tuesday, then Mass Effect the week after. CoD4 is missing a few things that I wish Microsoft would force on all developers like button remapping and X and Y sensitivity. Half Life 2 has them, so should every modern game.