SourceFabric has just released BookType, an open-source collaborative publishing platform designed to help authors, copywriters and reviewers write and publish a book on paper, web, tablets and smartphones.
"Booktype is a free, open source platform that produces beautiful, engaging books formatted for print, Amazon, iBooks and almost any ereader within minutes. Create books on your own or with others via an easy-to-use web interface. Build a community around your content with social tools and use the reach of mobile, tablet and ebook technology to engage new audiences."
Learn more at : http://www.sourcefabric.org/en/booktype/