Fellow handler, Swa, points out that new versions of PHP 4 (4.4.7) and PHP 5 (5.2.2) have been released which address many of the issues identified during the month of PHP bugs.  You'll probably want to consider updating as soon as practical.

References:
http://www.php.net/releases/4_4_7.php
http://www.php.net/releases/5_2_2.php