Popularity can be measured objectively by numbers. Coolness on the other hand, is totally subjective. A cool person or thing may not be popular, and vice-versa.
Someone I know did mix up both terms. There was some meme on LJ that measured how popular a user was. Well he was complaining about the validity of an instrument that tried to measure how cool a person was.
I think at Penn State, it's probably the engineering and business majors...and maybe also IST. Or it could just be that a lot of my friends were these majors and my perception is a little skewed.