Robin Good: Baker is an HTML5 open-source eBook publishing framework that makes it easy to create and format digital magazines and eBooks for the iPhone and iPad (some technical competence is required).
Conceived by Davide Folletto Casali and developed with his two partners Marco Colombo and Alessandro Morandi, the Baker Framework is an elegant and free solution to utilize the open standard HPub 1.o format to put together professionally-looking digital publications without needing to purchase or pay for a commercial layout tool.
Showcase of books created with Baker: http://bakerframework.com/books
Baker tutorial: http://bakerframework.com/tutorials/30/basic
Download Baker: http://bakerframework.com/down/baker-framework-3.2.zip
More info: http://bakerframework.com/