Correlation (or the lack thereof) between SAT scores and undergraduate GPA Answered
There's a preprint out on arXiv reporting an analysis of entering SAT scores vs. in-major GPA for four years of graduating students at the University of Oregon. The authors report a fairly low correlation coeffecient (0.35 to 0.5), with a long left tail in SAT scores. The latter strongly implies that university success is not well-predicted by the SATs. They also find a high correlation (0.75!) between SAT and GRE scores.
It's a very nice analysis, and a reminder that standardized testing is an excellent way to measure how well someone can perform on standardized tests.