In a new post to the SpinDrop blog, Dave Dash talks about his integration of the Zend Framework into a symfony installation - inside a plugin.

I originally intended to rewrite my Zend Search Lucene tutorial, but Peter Van Garderen covered the bulk of what's changed and I was too busy developing search functionality for lyro.com (not to mention finding inconsistencies with the Zend Search Lucene port and Lucene) to finish the tutorial. So I broke it up into smaller pieces.

I packaged Zend Framework into a symfony plugin. symfony is easily extended using plugins.

He includes the method he used to get the plugin up and working (downloading his custom ZF plugin) and how to use the Zend Framework Bridge to get it and symfony cooperating.