Yes, you're right, this isn't exactly "breaking news." It happened on Thursday, and since then, many of you have written Article III Groupie about Chief Justice Roberts's unfortunate slip of the tongue. So A3G wanted to blog about it, just to let you know that she's aware of it (and you therefore no longer need to email her about it).
Chief Justice Roberts's mistake is arguably made worse by the fact that he was speaking without notes.* It's sort of like when you go to a restaurant, the server takes your order without writing anything down, and then he or she completely screws up your order. If you're going to engage in the oratorical equivalent of going commando, you've got to keep everything perfectly clean...
* JGR's screw-up is especially surprising since he is no stranger to speaking without notes. He did not use notes during his lengthy Senate confirmation hearings, at the press conference announcing his nomination, and at countless oral arguments before the Supreme Court and other courts.