GM-less roleplaying

Just thinking out loud here.

There are several problems with GM-less playing, the first one being that reality is everyone’s bitch.
This means that people tend to be either too abusive of it, or too timid to mess with it.

De Profundis talks about the sort of game where anyone can introduce facts, and how this is tends to cycle into self-collapsing loops where one player will introduce something, say a threat, and the other will negate or deflate it. So you don’t get story and rising tension.

Star, Moon and Cross has rotating GMs, player input into the setting, players playing NPCs, etc. It uses Tarot cards.

A system for GM-less or everyone-GMing play needs to do several things, I think (I’m trying to define the goals before coming up with a system):
First, provide obstacles – difficulty, drama, etc. I think my main motive here is to take it out of my hands as GM to generate tension. Sweat out the dice instead… The idea is that the system forces (well, encourages) the group to set up real challenges.
Second, reward a player who takes up the GMing role for doing GMish things that are neccessary (generating setting, challenges, story).
Third, discourage abuse of GMing power (to benefit your own character – hosing other characters is actually part of the GMish job).
Fourth, enforce rotation of GMing roles/actions (provide some rule to keep the spotlight circulating).
Fifth, motivate the group to cooperatively make things harder for their characters (ties into the first and second point).