Book Sprints is the name given to collaborative authoring in a short time with the express goal of having a publishable book at the end. The Book Sprint concept was devised by Tomas Krag. Tomas conceived of book production as a collaborative activity involving substantial donations of volunteer time.
Tomas pioneered the development of the Book Sprint as a 3-4 month production cycle, while Adam Hyde, founder of FLOSS Manuals, was keen to continue with the idea of an "extreme book sprint," which compressed the authoring and production of a print-ready book into a week-long process.
During the first year of the Book Sprint concept, Adam and FLOSS Manuals experimented with several models of sprint.
Sugar Labs and One Laptop per Child Book Sprint, August 2008
Book sprints have generally taken place in areas of computer technology, where documentation has traditionally been tarred as the most irksome and unpleasant of tasks. Book sprints prove that nothing could be farther from the truth. They make writing fun by:
The result of the sprint is a book meeting the specifications of the community that began the project--in other words, it meets known needs.
Because book sprints involve open contributions (people can contribute remotely through a wiki as well as by joining the sprint physically) the process is probably most suited to books offered free online. Indeed, the goal of FLOSS Manuals embodies this freedom in a two-fold manner: it makes the resulting books free online, and focuses its efforts on free software.
FLOSSify - Digital Foundations Book Sprint, February 2009