By the same author of last year’s well-regarded front end drupal; This similarly-sized book is aimed more at beginners.
PHP
The Definitive Guide to Drupal 7
If last year’s professional WordPress is the must-have book for WordPress developers, then definitive is at least the equivalent for Drupal developers.
Joomla! Explained
Your Step-By-Step Guide
It’s closer to drupal than WordPress in terms of scope, though it takes its own approach in some areas, and that’s what this book will teach.
Pro Drupal 7 Development
Learn How to Use the Content Management Framework to Create Powerful Customized Websites.
Drupal’s Building Blocks
Quickly Building Web Sites With CCK, Views, and Panels
One question that is going to come up is how current is this book with the recent arrival of Drupal 7? Except for CCK, most of the content is still relevant.
Professional WordPress
Design and Development
Out of the over 300 books on WordPress, few get down into the into WordPress’ code itself. Professional WordPress is that kind of book.
Smashing WordPress
Beyond the Blog
Make your next WordPress site a smashing success (And make sure it doesn’t get smashed.)
Sam’s Teach Yourself Drupal in 24 Hours
If You Have 24 Hours to Spare, Why Not Learn Drupal?
WordPress 2.7 Cookbook
Get things done with WordPress without writing a lot of code.
Front End Drupal
Designing, Theming, Scripting
Tools and Techniques for Learning to Create Themes for the Drupal 6 CMS.