WP Zend Library plugin by wildmice is used to integrate the Zend Framework library into WordPress, making it available for both themes and other plugins. It does not include the ZendX extra library.
This plugin emulates the Zend Framework bootstrap file, without any application environment (because WordPress does that), and includes a configuration file for setting database connection parameters.
Zend Framework is an open source, object-oriented web application framework implemented in PHP 5 and licensed under the New BSD License. It implements a popular application design pattern called model-view-controller (MVC). In this case, WordPress becomes the ‘view’ instead of a Zend Framework application.
This plugin will probably work with versions of WordPress earlier than 3.2, but if you are running such an earlier version check your version of PHP. Zend Framework requires PHP 5.2.4 or later.
The author says: “This is the first version of this plugin and it has not had extensive testing. Consider it experimental and use at your own risk.”
Download: http://wordpress.org/extend/plugins/wp-zend-library/