Collaborative Authorship

Collaborative authorship 
is the act of co-creating and consulting within a group of people to create a project, in which the author of the project is the group itself rather than a single person. |
—http://en.wikipedia.org/wiki/Collaborative_authorship

Wikis / Blogs are good examples of colloborative writing.

Successful collaboration occurs when each participant [or stakeholder] is able to make a unique contribution toward achieving a common vision or goal statement. Supporting this common goal are objectives that have been generated by each of the participants. It is important for each participant to “feel” as though he or she has a significant contribution to make to the achievement of goals. It is also important that each participant be held accountable for contributing to the writing project. [Brown, C. A., 2007, East Carolina University]