I currently use latest version of php 5.2.x (5.2.14)

PHP 6 is in development but source is available and UwAmp includes compiled binaries of an old dev version.

php 5.3.x still faces some incompatibilities with some software (like IP.Board), unfortunately 5.2 series are now EOL'ed
http://www.php.net/archive/2010.php#id2010-07-22-1

Regards,
NewEraCracker.