Funny; I was just having this discussion with a couple of my club players just last evening at practice. Of the ones who want to continue playing after high school, some were looking at large, state-supported schools (Clemson, USC, VT, etc.) and others were looking at more academically rigorous colleges (Brown, Duke, etc.). At the larger state-supported schools, not many are going to look at grades as a draw for scholarship money--you get athletic scholarships for athletics, academic scholarships for academics--as long as the grades are sufficient for entrance requirements.
At a university with very rigorous academic standards, though, I think grades will come more into play when evaluating players; with the higher academic demands, athletic programs seem to be less likely to invest scholarship money in players unless their grades indicate that they will be able to stick with and complete the academic program while playing a sport. It would be risky to invest in players who are likely to (A) not pass courses and therefore not remain with the university for their years of eligibility or (B) have to drop out of a sport in order to meet academic requirements. So, some athletic programs will be looking for blue chip players regardless of grades, and others will be looking for blue chip players who can also make the grade.