I read part of the decision and the notes posted on it at WSJ. They make the headline sound stupid. One of the notes, with some emphasis added by me:

The court upholds the most high-profile piece of the Arizona law: the provision that requires police officers to check the immigration status of anyone they stop if the officers are suspicious of the person’s right to be in the U.S. However, the court’s endorsement of the Arizona provision takes on a tentative tone. The court says it’s unclear what the law means and how it will be enforced. At this point, it would be inappropriate to strike down the provision, the court says.

The next note:

Justice Kennedy says nothing in the court’s ruling forecloses future challenges to the Arizona law once it has been further interpreted and gone into effect.

Or as Kevin Russell says in Charles’s first link:

1. Police Checks. Section 2(B) of the law requires the police to check the immigration status of persons whom they detain before releasing them. The Court held that the lower courts were wrong to prevent this provision from going into effect while its lawfulness is being litigated. It was not sufficiently clear that the provision would be held preempted, the Court held. The Court took pains to point out that the law, on its face, prohibits stops based on race or national origin and provides that the stops must be conducted consistent with federal immigration and civil rights laws. However, it held open that the provision could eventually be invalidated after trial.

This is what Jan Brewer is calling ‘a victory’.