we're doing something like that in our current OSE game I am running. We decided to have an RPG entry a day thing, and I'm using some of them already in the game. All my games are "open world" in that I tend to write up a lot (perhaps too much but hey, it is fun for me) then share that for shared worlds.
We've talked about rotating GMs for the same game but have yet to do that. We had a couple of game systems that would work really well in (i.e. military squads type of things, where personnel may change in and out; would work for Traveller except I am the only one willing to ref that game).
Like a lot of things - I like the concept but have yet to really try it.