On his blog today, Vinu Thomas points out a faster way to run PHP natively on a pure Java server - Quercus. As a side benefit, it can also interact with the Java code already in the application/on the server.
Quercus is Caucho Technology's 100% Java implementation of PHP 5 released under the Open Source GPL license. Quercus comes with many PHP modules and extensions like PDF, PDO, MySQL, and JSON. Quercus allows for tight integration of Java services with PHP scripts, so using PHP with JMS or Grails is a quick and painless endeavor.
Quercus focuses on the integration of PHP and Java and allows PHP to access things like Java's JMS, EJB and SOA Frameworks. It works by compiling the PHP scripts into Java and run on top of the Quercus software as a native application.