This fell out of the design work we did during graphaphon, we should really create an 'authoritative' ERD-style diagram showing the relationships between our logical entities, so that people can see the relationships today between elements.
I would presume this could be done fairly easily in something like dotty/omnigraffle etc. Verne Lindner has volunteered to help with making this "pretty" if we need to as well.
I've shared some draft diagrams with Verne Lindner and we talked about the concept behind what message we are trying to share here, and how a diagram might be useful to different users. She's taken what I've got in raw form now, and will try to clean it up and make it nicer.