Anyway, Glenn Greenwald has cleared up my confusion:
[T]he court's ruling had nothing whatsoever to do with whether Bush acted legally or properly when he ordered warrantless eavesdropping on Americans from 2001-2006, when warrantless eavesdropping was a felony under FISA. To the contrary...the FISA court was addressing a totally different and much narrower question: namely, whether the warrantless eavesdropping which Congress authorized in the 2007 Protect America Act was prohibited by the Fourth Amendment's warrant requirement.
Ah, doesn't that ring much truer? And with something that subtle, you can see how Bush fans would claim vindication. Greenwald has some strong words on this aspect too:
[The lazy and ignorant media] report what "both sides" are saying, or -- as will be the case here, I predict -- the immediate storyline that "the FISA court vindicated Bush's spying and ruled it legal" immediately settles in (it has the advantages of simplicity and power-worshipping, an irresistable one-two punch for Beltway media stars), and then, no matter how many facts are marshalled or energy is expended to uproot it, it stays entrenched forever, rotting away and further infecting our discourse and distorting our collective actions with regard to our government's chronic lawbreaking. Today's orgy of ignorance is a nice little case study of the last eight years.
In closing, I should note that the WSJ discussion appeals to a different FISA ruling in 2002 that supports their broad interpretation. But I think it's possible GG and the WSJ are both right: The WSJ could still claim that President Bush acted within his constiutional powers (and cite rulings XYZ on the point), while GG is merely saying that the recent FISA ruling has nothing to do with that issue, and so Bush supporters should stop claiming vindication because of it.