WordPress Mobile Web Development Beginners Guide book is published by Packt Publishing and written by Rachel McCollin. Book contains a lot of information on plugins and themes you need for website, setting up mobile specific media queries, layouts and more.
WordPress Plugin Development Cookbook book is published by Packt Publishing and written by Yannick Lefebvre. Book contains 80 practical step-by-step problems with easy to follow solutions to most common problems developer can have when creating plugin for WordPress.
WordPress Top Plugins is rather unique book published by Packt Publishing. Book is written by Brandon Corbin, and it contains description and examples of use for some of the most popular WordPress plugins in use with introduction chapter on working with plugins in Wordpress.
Third version of the Chris Coyier and Jeff Starr amazing book Digging Into WordPress is released last week. I got my updated copy from Chris yesterday. I already reviewed first version of the book last year, so this is only a small reminder post.
Few months ago Packt Publishing published interesting book on WordPress 2.7 written by April Hodge Silver and Hasin Hayder. This is a guide for people starting with either WordPress.com or self hosted blogs. All chapters are easy to follow, with many screenshots that will help guide you.