The only quip I have with this book is the title "Practical Web 2.0 Applications with PHP" it should be called "Practical Zend Framework Applications using PHP"
There is not one example in the book that doesn't use the Zend Framework. That being said the Zend Framework is a great framework - by far the best web framework I've seen. I'm PhD student in Computer Science at UCLA whose dissertation research involves the web. I've used a lot of web applications and frameworks. Symfony, Drupal, Joomla, Ruby on Rails, etc.
Most of these applications and frameworks just suck - that is, it is more work using them than not using them and many severely limit what one can ultimately do.
I like Ruby on Rails but I love the Zend Framework. There are two big differences between the Zend Framework and Ruby on Rails: 1) they both promote MVC style programming but Ror forces you to use it everywhere and the Zend Framework allows you to mix MVC with simply using their framework as a library wherever you want. For example, I am building a social network but want to mix that with a related wiki. I can use MVC for all the social network code and use and existing MediaWiki (which is not MVC based). All I need to do is rewrite some of the mediaWiki code to hand over user authentication to my controllers.
2) it's Php based ... there is much, much more existing Php code to cannibalize for applications than Ruby code
There are some issues I have with the book. In places where something could reasonably be done in multiple ways the book only shows one without any explanation why that way was chosen. For example, in the installing Zend chapter the book tells you to edit the httpd.conf file to set your paths. Most people who use a commercial hosting company don't have access to edit httpd.conf or restart the server. There are ways to reset the path within the Zend bootstrap (which I did) but if I didn't know how to do that I would not have been able to get the examples to work without setting up a server locally on my machine.
Also the bootstrap is left in the index.php file when Zend recommends using the index.php to call the bootstrap.php file from a non-public web directory.
The Zend Framework is only a few months old and this is by far the best web framework out there. There is only one other (decent) book on the framework. This book is about the Zend Framework and only marginally about "Web 2.0" (you use Google maps). The book that should have been titled "Practical Zend Framework Applications using PHP" will teach you how to use the best web framework out there. If the next book shows one how to really use web services, ajax and present web services using the Zend Framework then it can be called "Web 2.0" not this one.