I recently needed to install Zend Optimizer which was required by a ZenCart addon using Zend Guard. Zend Guard encrypts some or all of a PHP application to help protect its contents from being copied or modified. So I was typically like to install everything on CentOS using the yum package manger to make sure that updates for all applications are uniform and easy to do.
The actual package that needs to be installed to install Zend Optimizer is called php-zend-optimizer and isn’t readily available in many yum repositories. On a typical CentOS installation I add a couple extra yum repos including rpmforge and a repo that provides ruby based packages for CentOS. Anyhow after awhile of searching I finally located the atomic repository which did include the php-zend-optimizer package.