"Web Collaborator coordinates collaborations automatically, keeping backups of every revision ever made to the project, letting you see who made the changes, and allowing you to focus on the work instead of managing the work."
There are three different aspects of this tool
1) A discussion aspect of some sort where collaborators talk to each other
2) the project itself. This part has wiki-like capabilities where the members of the group can each add, edit, or delete things from the project and the changes show up instantly. You can print out a pdf form of the project at any time.
3) Also a la Wiki, Web Collaborator allows you to go back to previous versions of the document.
Anyway, looks interesting, and I'm itching to try it out. Anyone have a collaborative project they need to work on? :-)