We have just upgraded our servers to WHM/cPanel 11.30.6 (build 4) CENTOS 5.8 x86_64 standard.
We have decided to leave the present versions of mysql and php until all our clients are able to upgrade their custom scripts so there is no conflicts with php 5.3.
We advise everyone to please do this asap as we will be forced to upgrade to php 5.3 and above before too long.