The latest PHP versions are available for CentOS Plesk Panel admins. If you are using my YUM-repo as suggested, the update should be a painless one.
I managed to get the FPM running for PHP 5.4, for the PHP 5.5 it is still pending. Example:
# service php-fpm54 status
php-fpm (pid 4318) is running...
Please note, that the FPM is still work-in-progress and it may contain bugs.
The latest PHP FPM has a fix for CVE-2014-0185. It is not a really dangerous one, it just takes care of 0666 permissions for the FastCGI unix-socket. It can be considered a security flaw if any local user can execute code via FastCGI-interface. Most web-servers don't have many local users, but this flaw can be combined with other security issues to get more gain out of it.