Here’s a book from Bruce Perens’ Open Source Series called PHP5 Power Programming.
This book deals with :

• Expert PHP 5 programming techniques, direct from PHP 5 co-creator and key developers
• Definitive coverage of the PHP object model, design patterns, XML/SOAP integration, and more
• Solid introduction and expert insights into performance tuning, PEAR, extensions, and database access
• The definitive introduction to PHP 5’s advanced features!
• The definitive introduction for today’s most powerful PHP 5 techniques

In this book, PHP 5’s co-creator and two leading PHP developers show you how to make the most of PHP 5’s industrial-strength enhancements in any project—no matter how large or complex. Their unique insights and realistic examples illuminate PHP 5’s new object model, powerful design patterns, improved XML Web services support, and much more. Whether you’re creating web applications, extensions, packages, or shell scripts—or migrating PHP 4 code—here are high-powered solutions you won’t find anywhere else.

You can download the entire book from Prentice Hall (click on the download link at the Prentice Hall site to get the entire book in pdf):
http://www.phptr.com/title/013147149X