A few app requires PHP 5.2.x but major repositories is yet support anything higher than 5.1.6 at this time. Recompile PHP is a pain also.
Remi maintains a repository that can save your 1 day or 2 if you have such need.
rpm -Uvh remi-release-5*.rpm epel-release-5*.rpm
You now have Remi repository on your system. It's disabled by default, and I recommend you leave it as is. To install from remi, run the following:
yum --enablerepo=remi update php
I use remi to install php and its related stuff like GD, mcrypt, etc. As well as MySQL. The repository rocks!