The GRE is pretty much a repeat of the SAT, minus the new writing section, plus the analytical section, which is basically logic games. I needed to take the GRE for admittance into an Economics PhD program, and the school wanted close to perfect scores on the quantitative and analytical and didn't care at all about the verbal. Luckily, I got 800 on both the important sections:) There was an Economics subject GRE, but only a few schools wanted to see scores. Really, I think most graduate programs use the GRE as cross-check of whether the applicant has decent reasoning abilities. They take a much closer look at your grades and the courses you've completed. Graduate programs aren't necessarily looking for students who are more than 2 standard deviations above the mean - they just need people who are smart enough for the work.
Coincidentally, I am currently enrolled in an M.Ed. program for secondary math, and yes it is true that the typical students in education programs do not have stellar scores on the GRE. But, if you consider that teaching is one of the lowest-paid careers that someone would need a master's for, it becomes a little more understandable that the scores would be on the low end. Remember that only college grads who are pursuing higher degrees take the GRE, so that is typically a smart group. If you want to see higher average GRE scores among educators, you are going to have to start treating teachers as professionals. (Not singling anyone out, just the USA in general!)
