Multi-GMs...it can work on a limited scale. Mostly it works if one GM is Primary and has The Vision and Main Plots and the other GMs run combat, secondary plots, complications, throw up ideas, etc. Basically grease the play-wheels and say things like, "No, you can't swallow a nano-pill you invented using Jury-Rig to fix your Skinweave" or, "Wednesday Night at the Forlorn Hope and the music is a clean riff on early 30s Jazz. It's also the scene for three men in suits at the back tables talking quietly to a young woman in heavy combat leathers. Anyone present check A/N and Gen Knowledge or Expert: Corporations, please."
Stuff like that. Fun stuff!
Usually, you want to have the theme and setting of the game strongly established first, though, as well as the rules modifications and character playstyles in place.
In PbP, where you have the freedom to create your own scenes or modify existing ones within limits, we are all sort-of GMs. Sort-of. The scene modifications are going to be tricky. We'll see how it works vis-a-vis in play first.
In terms of rules, once we all know them, we can all run them. Right now, eraser has the best grasp on IU and Sue has run games for, apparently, a billion years, so they get a lot of leeway and responsibility.
The other trick is having a character in-play. I don't plan to, myself, and if someone is adjucating/explaining live play, they shouldn't have a character on the line either. At least not at first.
Also, since it's come up: if anyone is trying to avoid Selling Out in order to get more money or resources by use of perks or loans or even a great background, don't.
Selling Out is a key choice in character creation and I'd rather not see it bypassed.
Also, if anyone hasn't done a Lifepath, that's pretty cool and worth your time. Remember to roll for the Event Years, but you can pick the personal details, of course.