As this post on the Zend Developer Zone mentions, Zend is joining in on the European WinPHP Challenge by offering additional prizes to the winners.

Zend is announcing today that they are joining up, and are offering as prizes to the 3 winners a one year subscription to Zend Server, and licenses for Zend Studio. The winners will be announced at the Dutch PHP Conference in Amsterdam.

This year's challenge has already started, so the registration is closed but you can keep up with the (six) contestants on this page of the DPC wiki.