I'd be interested in what everyones "definition" of a rivalry is. Is it that you play them often? Is it geography, or have some score to settle?
I think it can be a little of each. I think of Miami and Tennessee as rivals, but we hardly play either team anymore. The next time we do, I'll consider it a major, if infrequent, rivalry game. But, I also do not consider Pitt to be a rival, even though we play them often. I guess it has to do with the program being in the same class and if they are big, meaningful games.