There's one thing I don't get about this whole affair. I've served on Institutional Review Boards and as far as I can tell so far, Facebook has violated federal law regarding protection of research subjects. You almost always need prior informed consent, even if the only risk is that the subject might feel sad, and in those few cases where deceit is an essential part of the experiment, the IRB closely monitors the situation and post informed consent is required. As far as I can tell from the news, this project was never reviewed.
So if there is an enterprising attorney reading, this sounds like ideal class action territory.