I have learned few points related to age from different forums and by talking to few current students at B-schools:
1. If you have exceptional profile (in terms of work, education or extra curricular activities)- forget the age.
2. If your profile is similar to the mass applicants of a particular school but your age is way below or above the average age - then you would have show that you have an edge over the others. Additionally, you have to tell adcom 'Why MBA Now' (and why not earlier or later). This becomes very-very important if you do not fall near to avg. age (or experience).
3. Most people agree that H/S/W are more hesitant in taking older applicants. One of the reasons for this trend could be this - these schools already get top candidates with excellent profiles. so there is no reason for them to admit older applicant unless they believe that this candidate is far better than other younger applicants.
4. You can not change your age, anyways. So, don't be discouraged and give it a shot. For better results, prepare excellent application. Your story (why MBA, why now and why this school) should make sense to adcom. While selecting the schools, try to find schools that have higher avg. age. In addition, make sure that your career goals (and why now) fits to the school you are applying to.
These are my opinions that I have formed based on my research. I am an older candidate too and hence did some research to find out where do I have better chances. No one for sure knows about it but as there is a practical limitation on the number of schools one can apply for, it is better to select the schools wisely.