Can we really say it's a "monopoly"? I would agree if users had been brainwashed to the point where they would refuse using anything else than Facebook Connect,

Can we really say it's a "monopoly"? I would agree if users had been brainwashed to the point where they would refuse using anything else than Facebook Connect, but, as the authors mentions, there are a lot of possible alternatives for them to use (or they can roll their own). There is no real Facebook monopoly imposed on website publishers -- there is just a monopoly imposed on the users of those websites where Facebook connect is the only option or the only visible option. I agree that it's a concern, though.