(Also, is there some independent corroboration, besides from the publisher of the test, about how g-loaded the current version of the SAT is?)
Charles Murray has a few words on the subject (note that his name is linked to an article he wrote):
Despite the College Board’s rhetoric about revamping the SAT to reflect curriculum, the changes in the test in 1993–1994 probably did not have much effect on the SAT’s power to measure g—in the jargon, its g-loading. (I would not make the same statement about today’s SAT, which has eliminated the highly g-loaded analogy items and added a writing component that carries with it a multitude of scoring problems.)
He also makes the point that smarter kids tend to get higher scores on any test, be it an achievement test or a pop quiz, and that any mental test has some g-loading in it. Fair enough, but this doesn't mean that the scores on current SAT are a proxy for IQ. The
range of scores doesn't even go to three standard deviations above the mean, so at best even if it
isa proxy for IQ scores --- which I don't think it is --- the SAT has a very low ceiling at best.