On firman's blog today, there's a new post that asks the question "Which is A Best One?" when looking at PHP MVC frameworks.
So many open source projects MVC pattern in PHP, you can see the complete list of the projects at http://www.phpwact.org/php/mvc_frameworks. I just can say wow! then wondering which one i should be use? Some provide the basic framework, another provide more than MVC. Some projects are ported from another projects such as Struts, Ruby on Rails and so on, another brings their own concept for implementing the MVC pattern. I have no idea, which is a best one. Zend also participated on this "race".