If I think about it, it really is the only method I’ve done, other than truly collaborative (i.e., simultaneous) GMing, where one GM runs the story and the other gets minis, prepares maps, tracks initiative, makes sure evrybody is moving along smoothly. This method is used for larger groups of players, especially kids.

We’ve also tried divided party once in a huge fight that took place bout outside and inside of a building, with one GM dealing with the outside, and other the inside. Worked OK for that session, but the situation must be such that dividing the party makes sense and polling between different groups would be too slow or reveal too much to the players whose characters are not present.

For the GM’s in our group, the collaboration pays off especially in design (as we do not use published adventures) – actual play works usually better with only one GM in charge, although the meta-PCs can point out some forgotten details if needed.

Shared world can work very well– I’ve enjoyed playing and GMing in that format, though it’s been a while. I’ve been the covert GM at times, often while the “actual GM” learns the system. Though everyone enjoys a confidante…

Divided parties and shared world co-GMing are both interesting, but I’ve only encountered them rarely– particularly at cons or in Larps for divided party.

Also timely as I’m about to start my first game, and we’ll be using the Rotating Campaigns model.

For a little while now we’ve been switching off about every other session between our regular D&D game and occasional True20 adventures set Manhattan in 1890. I’ll soon be taking over as the “alternate” game for a least a while as we run through a short 4E adventure I’m working up. I think our current GM is going to be pretty happy to have every other week off and to get to play as a player again!