From PHPEverywhere this morning, there's a review of the new George Schlossnagle book - Advanced PHP Programming.

Reading Advanced PHP Programming by George Schlossnagle feels like looking into the mind of a true PHP guru. I know George has an intimate knowledge of the PHP internals and Zend engine, and is an expert on PHP performance tuning. The book also covers PHP5, and most of the examples are in PHP5.

The range of technologies covered is very wide, including Templates, Caching, Databases, Sessions, RPC, Server Farms, Proxies, Benchmarking, Profiling, and Zend Internals. All the parts I read show George has spent a lot of time thinking and designing technologies in these areas. His discussion on performance tuning PHP is particular good. In many places, I can remember going through the same blind alleys he went through. At the end of each chapter, there is a further reading list - nowadays one book is never enough to cover everything. I also have a feeling that George is careful to write about areas in which he has the appropriate expertise. For example, I did not see any reference to PDF or GD usage in the index or in the text.

All of the reviews that I've seen for this book have been amazingly positive, so if you're looking for a good place to start once you've mastered the basics, then Advanced PHP Programming might be worth a look...