We fully support Zend Framework on all of our shared and reseller hosting servers. While we do not have a system wide install available for use, all users are able to upload the framework themselves and run it from within their account. All of the required modules are loaded and Zend Optimizer is installed.
To install it, upload Zend to the directory your application is in. For example, if your application is in /home/username/public_html, you should upload Zend there (making it's path /home/username/public_html/Zend). If you decide to install it below your home directory, you'll need to add an include path to your PHP scripts for that directory.