Per an announcement today at Zend Conference 2006, GData support is now available in the Zend Framework:
The Google Data APIs provide a simple standard protocol for reading and writing data on the web. With the Google data APIs, developers can mash up services like Google Base, Calendar, Blogger, and CodeSearch.

Zend Google Data Client Library provides a PHP 5 component to execute queries and commands against Google Data APIs from your PHP applications.
Check it out and let us know what you think!