I opted in as well. I was sort of disappointed that the results of the "opt-out sub-experiment" weren't discussed in this statement. He's mentioned it in interviews - on NPR and repeatedly on reddit, at least - that he's got huge feedback on that little decision. It's also something that people, present company included, love to talk about. It would be interesting to see how many people decided to opt-in because he defaulted to opt-out.