Not to take away from this work, but the title is wrong, or at least needs more specification. There's at least one book that was 100% crowdsourced before this:

"Amazing But True Cat Stories"... http://bjoern.org/projects/catbook/

All of the stories were written by users on Mechanical Turk, around 2008. The project got a lot of press and attention at the time, on O'Reilly, Boing Boing, and the like. The "author" also wrote a how-to on Instructables: http://www.instructables.com/id/Dont-Do-It-Yourself-Start-a-...