Update: Much is being made in the press that the Solicitor General apparently did a poor job arguing the case today. That doesn’t matter a whit. Oral argument is usually something of a Kabuki dance. A good argument rarely changes minds that were not persuaded by the written briefs, nor will a bad argument fail to sway a vote that would would otherwise by the advocate’s. The written briefs–and in this case, the politics–are what matter. I have no doubt that all of the the justices knew how will vote before the oral arguments began, and those decisions will not change over the course of six hours discussion no matter how well or poorly presented.
However, the way justices ask questions or make comments during oral argument can sometimes reveal how the justices are thinking. That is apparently what Toobin and other commentators who have voiced similar opinions about the individual mandate being in trouble seem to think happened today.