The ThinkPHP blog has posted this pointer to some new information on an anticipated piece of software in the PHP community - the Zend/Eclipse collaboration on a PHP IDE. The post provides a link to this new information over on the Zend site, a short introduction to installing the extension.
The preview page links you to the files you'll need to install the preview release as well as some simple instructions to get it working. There are three different ways to install it - downloading an Eclipse WST file, grabbing the module by adding a new update site, and downloading a Zip file with everything you'll need.
Remember, this is a preview release, so the functionality isn't 100% complete. There have already been some bugs/issues posted on the ThinkPHP Blog entry reflecting this.