So Chief Justice Roberts decided not to strike it down (the other 4 Republicans would have invalidated the healthcare act in full).
He's really threaded the needle here, by finding the mandate to be a tax for purposes of assessing its constitutionality but not for purposes of the Anti-Injunction Act, which would have required that the entire issue be put over. Roberts argues that labeling (whether or not Congress calls it a tax) controls for statutory interpretation purposes but not for constitutional purposes.
At a first glance, Scalia's 65-page dissent is less hysterical and intemperate than we have come to expect from him. I wonder if he thought it had a chance to be the opinion of the Court when he wrote it.
I must say, I still think Roberts' agreement with the other 4 Republicans that the action / inaction line makes the mandate impermissible under the Commerce Clause is just silly. Here is the key Roberts sentence on this issue: "The power to regulate commerce presupposes the existence of commercial activity to be regulated." If you recognize that health insurance is prepayment for future healthcare services, that is a complete non sequitur.
Whether or not the 5-4 Commerce Clause vote against the mandate will prove more broadly consequential in future policy battles, who knows. It may depend on whether there is a political price to pay for relying on the taxing power as a constitutional matter (even though you don't have to expressly label it as a tax for this purpose).
Note, by the way, the implication that Social Security privatization (such as the 2005 Bush proposal) is potentially unconstitutional under the Commerce Clause, and would need the taxing power to be upheld. Likewise, one could probably structure the substance of the Paul Ryan Medicare plan in such a manner as to be beyond Congressional powers under the Commerce Clause challenge, although again this doesn't matter given the taxing power.
Bottom line, evidently Chief Justice Roberts didn't want the Court that bears his name to go out as far and as visibly on a hyper-partisan limb as striking down the Act would have necessitated. I find this cause for relief, although he may continue to act more aggressively, in full cahoots with the other four, when the level of public scrutiny is lower.