|The Big Model|
You're heard of "GM-less" games, right? Except that there aren't any. Typically when people say that, what they mean is that the various things that GMs traditionally do are now distributed around the group in some way. So GM-ful is a much more sensible term.
The Technique of distributing GMing Tasks across all the members of a role-playing group, up to and including re-distributing them during play, as opposed to concentrating them in one person. Coined by Emily Care Boss. See An approach for mechanics and innovation.