I've always thought that the “profile" of a college commencement speaker says something about the college where they're speaking. For example, I don't think you would find Rush Limbaugh speaking at Reed College. Conversely, I doubt that Van Jones would address graduates at Brigham Young University. Colleges who maintain a left-leaning stature usually bring in more liberally oriented speakers, just as conservative schools tend to favor right-of-center notables.
This year, there were three high-profile controversies involving students protesting their school's choice of a commencement speaker. Perhaps the highest-profile case involved former Secretary of State Condoleezza Rice at Rutgers University in New Jersey. Here's a quick recap of that from CNN: