The U of Idaho has modified its IFC and Panhellenic rules on guest lists for parties.
See article that includes background information:
http://www.uiargonaut.com/content/view/9334/48:testset/
Guest lists for parties “now must include a guest’s full name, whether they attended or did not, and whether they are over or under 21 years of age.”
The changes, at least as I understand them from the article, don't seem especially rigorous, but I may be missing something. At least there seems to be an attempt to help organizations think about the over-21 and under-21 situation at parties before the event gets under way.