PBS had a piece on it this afternoon saying that a third of the Calvin faculty protested the visit. I must say that doesn't sound like the Calvin faculty that I know. I imagine they are exaggerating or lying.
As far as I can see it's true; 1/3 of the faculty at Calvin signed the letter, as well as some administrators and 300 students (past and present). They were also able to raise enough money between them to take out a full-page ad in Friday's Grand Rapids Press, as well as a half-page ad in the Saturday edition to run their message.
Calvin's president was just on the Sunday evening newscast talking about how it's a good thing for the college, because it dispels the idea that it's a monolithic institution, and that there's a diversity of opinion on campus. From what he was saying, apparently being a haven for conservatism hurts the college's marketability.