I agree with much of what has been said already in this thread. Predicting one's chances of getting in anywhere based on quantitative information like GREs and GPAs is essentially impossible (as long as they meet a certain threshold). It is also true that Cornell's Psychology program is fairly small and they don't admit many new students. It really is all about fit. In applying to graduate school, I read this so much it almost seems like a cliche, but it is so true! Most importantly though, it's how you convey that fit in your personal statement.
Also, I encourage people who are interested in Developmental Psychology to look into Cornell's Developmental Psychology program. I will be attending there in the Fall. For reasons that are unclear to me (and the faculty!), the Developmental Psychology program is housed Cornell's College of Human Ecology, field of Human Development (HD), while their other Psychology programs are housed in their College of Arts and Sciences. In either case, your degree is a PhD in Psychology.
The Developmental Psychology program has its own faculty members and admits it's own students--slightly larger cohorts than the CAS Psyc program (I think they aim for about 5-6 students); however graduate students from each program have the freedom to take courses from either department, and are sometimes required to do so. For example, this Fall the HD department will be offering a quantitative methods course that both CAS Psych students and HD Psych students will be required to take. I will also likely be taking a course in Cognitive Neuroscience offered by the Psychology department. Also, the new fMRI will be housed in the same building as the HD department
My impression is that the distinction between the two programs is largely historical, and that graduate students often have faculty from both program sit on their committee chairs.
Just my 2 cents, as I probably would not have thought to look for into Cornell's Developmental Psychology program had I not been applying to work directly for a professor who's work I was already quite familiar!
Link: http://www.human.cornell.edu/hd/index.cfm