This new post on Doug Brown's blog compares two of the more popular PHP frameworks - the Zend Framework and CakePHP - in an overview of features and general usefulness.
The Zend Framework, developed by Zend Technologies is an open-source, object oriented web-application framework implemented in PHP 5. It is widely known as ZF and is developed with the purpose of making things easier for PHP developers and supporting best practices at the same time. CakePHP too, is an open-source web application framework used for creating web applications written in PHP. It is developed by Cake Software Foundation, Inc. It is written in PHP and is based on the model of Ruby on Rails.
He touches on licensing, the components available for each, how both have an "install and go" mentality (little to no configuration required for a default install) and which he believes is good for what kind of developer/project.