I think maybe it depends a little bit on which university it is: perhaps a small university will not have enough money to hire a big dedicated PR office, so they will rely more on materials submitted directly by the scientist and stick closer to reality. But the PR offices of big universities (in particular MIT) put out pure hype which is very precariously connected to reality. A lot of work goes into these press releases (they will send someone from the PR office to interview the researcher and so on), but the work is not really aimed towards providing an accurate summary of the research...