This is a great idea. It's a bit confusing to use right now, but I'm sure it'll be excellent in the future. I think there's a lot of room to improve the publishing workflow for WP users. I would love to be able to not only collaborate, but consolidate my entire publishing workflow to WP - ideas > rough draft > final draft > published. Only having one draft type and keeping lists of ideas elsewhere online gets a bit untidy and time consuming for me.