Samstyle PHP Framework - all you need for fast web development prepared for Web 3.0
You can use CodeIgniter and include some of the Zend classes, like Zend_Feed_Reader, Zend_Service_Twitter etc. They can be used separately.
See Symfony. It's a full-stack framework, a library of cohesive classes written in PHP.
Symfony is based on the classic web design pattern known as the MVC architecture (details).
It provides an architecture, components and tools for developers to build complex web applications faster. Symfony allows you to release your applications earlier, host and scale them without problem, and maintain them over time with no surprise.
WEB3.0 doesn't exist! Cakephp is written to work both with php4 and php5. There are a lot of plugins, helpers for Cakephp, on http://bakery.cakephp.org
in Cakephp you can use Zend's libraries, just like any other libraries.