The criteria for diversity are extremely broad now, and include not only race, ethnicity, etc. but also economic hardship, first person in a family to attend college, women in the economic profession, and other backgrounds not well represented in our faculty. They also include people whose research and/or teaching is directed at increasing diversity and equal opportunity. Examples of appropriate backgrounds and activities are at http://goo.gl/IA3lo.If you click through, it is pretty clear that it is really all still about narrowly defined demographic diversity, with just enough fuzziness to avoid legal troubles.
I don't have a problem with some amount of demographic diversity; I think it is good for students and faculty to meet faculty and other students who have had different life experiences and there is some support in the literature for the value of demographically similar faculty role models. But it sure would be cool to find some direct mention of intellectual diversity as well. One might imagine that it is a sort of diversity that would really matter at a university. And it would be nice if the whole process involved less misrepresentation (i.e. it is in fact logically impossible to combine affirmative action with equal opportunity) and obfuscation by the university.