Let's begin with predictive validity. Among the countless studies done on this subject over the years, not a single one has failed to find a high correlation between SAT scores and academic performance in college, as measured by grades or persistence. On a personal note, during my ten years as Provost of SUNY, I had my institutional research staff repeatedly review the relationship between SAT scores and academic success among our 33 baccalaureate campuses and their 200,000 + students, and found - as all the national research has confirmed - a near perfect correlation. SUNY schools and students with higher SAT profiles had higher grade point averages and markedly higher graduation rates. (boldface is mine--Darren)
You should read the whole thing.