[bzbarsky]

Yes, but is that correlation after controlling for IQ and work ethic? Because family income correlates with IQ and work ethic...

As far as I can tell, the thing the SAT really correlates with most is the thing it's actually designed to predict: ability to succeed in college, as measured by college GPA. (In particular, the correlation between college GPA and SAT score is higher than between college GPA and high school GPA.)