I remember a few years ago Oprah having a show on this very subject, where she declared, "The older a woman gets, the shorter her hair should be," and mentioned how older women with long flowing locks reminded her of the Wicked Witch. I see her theory didn't go very far given her current hair length and age.
Personally, I don't see a correlation between hair length and age, but I do see a relationship between hair style and one's perceived age (the age people assume you to be when they look at you). In other words, seeing a mature face with a young-ish hair style (and young-ish clothing) can be discomforting. At least, for me it is.