I will be 27 when I begin medical school. The "average" matriculant is 23 or 24, I believe.
Although I do sometimes regret not entering medical school earlier, and there is one legitimate age-related concern (namely, at what point in my training/career I will decide to have children), I honestly wouldn't trade my life experiences to have those years back. I have had the opportunity to enter the workforce, live on my own with no parental/institutional support, and grow in ways that I never experienced as an undergraduate college student. After 3 years of research, voluteering, teaching, working with many different populations, and traveling, I went back to graduate school to get my MS, and I found that I connected much better with my classmates (of MANY ages, from 20 to 50+) and, especially, the faculty. I was able to communicate with my professors in a much more meaningful way then when I was an UG going to office hours. I found that they treated me more as a peer than when I was an UG.
I believe that my being somewhat older is absolutely an asset. This was confirmed by the Dean of Admissions who interviewed me at one of the schools that I was accepted to. I have found that I have been able to relate to other adults much more easily and effectively than when I was 21 and fresh out of college. To be honest, I look at those college "kids" now (as my friends and I affectionately call them), and wonder if I was like them, 5 or 6 years ago. I feel like I am at an entirely different phase of my life, and I am much more focused now. But perhaps that is simply my own personal journey, and does not apply to everyone else.
My point is that age need not be an issue, and should not be a discouraging factor for non-traditional applicants. I, personally, would rather teach a group of people who had had the time to experience real life and get a lot "out of their system"...I think that these students are better prepared to focus and communicate effectively. I don't know if age has any correlation with test scores or grades, but I would be interested to see if there is any correlation with the "quality" of physician that the student makes (how to measure this, however, is an entirely different debate)
Old Farts, unite!!!