From the adcoms I've spoken with, it's more of a low (reject) pile, a range of possible applicants, and a high mcat pile.
The point being, if a school has an absolute cutoff of say 7 minimum in each subject, then any mcat below 21 at that school goes into the low reject pile.
From the low value to about 36, there is a definite range of applicants who are more and more qualified as their mcat rises.
At 36+ though, it gets kind of pointless to discriminate between candidates. We are talking a couple of questions per section at this level. Three candidates who are 36, 40, and 43 are more likely to be judged against each other based on other factors besides their absolutely stunning mcat score. Take a look at the AAMC gpa/mcat table, the payoff from 36 to 45 is negligible, especially amongst the high gpa candidates who got that score in the first place.
I've been flamed for posting this before, so here's my disclaimer: no I haven't talked to every adcom in existence. No I haven't actually watched them place applications into physical piles. No these rules aren't set in stone. But I have spoken with adcoms at regional medical schools, I have examined posts by adcoms on SDN, and you can examine the publicly available AAMC data tables to see for yourself where the curve starts sloping up on the low end and where the curve flattens out again at the high end.
