Yesterday, my review copy of Garvin Hicking's book "Serendipity - Individuelle Weblogs fur Einsteiger und Profis" (Open Source Press, 39,90, ISBN 978-3-937514-54-3) was in the mail. Unfortunately, this book is currently only available in German, but I'm sure Garvin (or someone else) will translate it and publish it (maybe with the nice guys at Packt publishing?) soon.
He notes that the book (the massive book at 750 pages) covers just about everything you'd ever need to know about the Serendipity blogging system. Christopher specifically mentions a few things - a good summary for installation and configuration, a meticulous list of the plugins and the chapter that focuses on administration and security.