With the embodiment of Zend extension and optimizer in PHP 5.5, the demand to have better documentation became more clear and apparent. In addition, PHP contributors need to write more extensions and take utmost care of core PHP attributes.
Read more about PHP discussions and visit http://www.phpclasses.org/blog/post/207-Better-Documentation-for-PHP-internals–Lately-in-PHP-podcast-episode-35.html.