Oh goodness...
At Mizzou... PHC, IFC and NPHC are trying to form a tri-council in order to bring unity to all Greeks on are campus. I think it's an awesome idea, and I really hope they're successful. Right now, there doesn't seem to be much interaction between PHC/IFC and NPHC organizations. (I group PHC/IFC together because those groups tend to socialize most with each other. Not only in socials and parties, but in events like Greek Week and Homecoming... Alpha Phi Alpha is the only BLGO that has chosen to participate in Homecoming...)
As for your average student's view on the relations... well that all depends on the student. A member of an NPC sorority wrote an article in our independent student newspaper in 2004 accusing members of an NPHC sorority of tearing down philanthropy banners and vandalizing property in Greektown while wearing their letters, explaining that the organizations should be separate from each other. Personally, I believe that individual to be very closed minded, as her accusations were not at all verified or proven... there doesn't seem to be a doubt in anyone's mind that her claims were completely false.
The only thing she seemed to accomplished was making ALL Greeks angry... many protested and supported NPHC and all of it's organizations. There was an article focusing on one of the protests that can be found here...
http://www.themaneater.com/article.php?id=18502
It's amazing that one person can hurt the reputation of not only the NPHC sorority she was accusing, but her OWN organization and all the NPC sororities... which she is representing. We have had a couple of women at Mizzou recently that have made one bad decision that have made us all look horrible.
We recently had an event for all Greeks where the three governing bodies came together to talk about the idea of a tri-council... they seemed really optimistic that, in the future, relations could be strengthened and all fraternities and sororities would be participating in events like Homecoming and Greek Week.