I have Plesk 11.x installed on my CentOS 6.2 x86_64. I configured my PHP to load Zend Guard Loader. But know when I check php configuration by php -v the output is:
PHP 5.3.3 (cli) (built: Jul 3 2012 16:53:21)
Copyright (c) 1997-2010 The PHP Group
Zend Engine v2.3.0, Copyright (c)...