I was thinking about making this using the same method as I did in The War Of Eden Multiplayer Server. I thought each member could get their own area to build in, and it would be on the new terrain gen. Each player would get assigned times to build during the day. For Example:
Dblcut3- 4:00-5:00 EST
Cazybert10101- 5:00-6:00 EST
We'd have a whole chart for it. Anyone could join, and build whatever.