Jim Plush got impatient for Zend to update their Zend Studio Plugin for Mozilla and Firefox, so he did it himself.
Again, I can't wait any longer for people to update firefox2 extensions. Here is a download link for the Zend Toolbar Extension for Firefox 2: http://www.litfuel.net/plush/files/ZendFirefoxToolbar-1.5.1.xpi.
The Zend Studio Plugin for Mozilla/Firefox allows developers to debug and profile PHP applications (running on the Zend Platform) through the web. Check out Zend's page for more information.