"One partner is Yahoo, which is helping Zend with version 6 of PHP..."
http://news.com.com/
"... six months after Zend's last major product announcements, when it unveiled ... and PHP 5."
http://www.internetnews.com/dev-news/article.php/3456771
Translated from German: "Currently, the language [PHP] consists of Zend-Core which is developed exclusively by 20 Zend employees"
http://heftarchiv-cw.computerwoche.de/index.cfm?pid=304&pk=1208251