My senior year in college, Playboy was presenting layouts of a co-ed from each of the schools in our confrence. The co-ed selected from my university was in a sorority. While I'm not sure of if sorority afflications were included with the images, the woman was asked to return her pin from Nationals. The initial reaction was well publicized, since the woman didn't see her actions as unappropriate, while her sisters and her nationals did. Unforunitly, I don't know if she ever did return her pin. Oh and my university is a large state school.

As far as whether or not its grounds for expulsion. Examine your documents and traditions. Would your photos compromise the principles that your sisterhood is founded on? If you can answer yes to that, then you have your answer.