The text and the source code for the Hadoop illuminated book, see http://www.hadoopilluminated.com

The book is written with docbook, http://code.google.com/p/docbkx-tools/
To generate the book in HTML and PDF, do this:
    $ mvn clean pre-site

References:

* xsl formatting reference : http://www.sagehill.net/docbookxsl/index.html

* docbooks quick reference : http://docbook.org/tdg/en/html/quickref.html