DGP,
I know there IS a National Multicultural Greek Council. I haven't heard about it in a while, but one does exist. There are about 8-10 orgs involved and most of the orgs are on the east coast. When I found out about it like 2 yrs ago, they were still trying to get everything together (Constitution, etc, etc) and then they were going to open it up for others to join. However, I just saw on one of the orgs' sites that they had a conference recently (w/in the last year or so). It was a picture from their 5th Annual Conference. But there were no more details. So I have no idea what's going on with it now. It seems like they are functioning but I have no clue if they are accepting other MC orgs. One of the founding orgs used to do updates about it on their website, but they don't do it anymore.
I'd like to look into it more, but I'm kinda swamped w/ work from my sorority and all.