Caucho (the maker of Resin) is positioning this as a PHP/Java bridge which
- allows PHP applications to be deployed over a Java application server and leverage Java infrastructure: JDBC, JMX, Web Bean (JSR 299), EJB, etc. WordPress was deployed over Quercus in few minutes .
- allows Java to use PHP as view component, in the face of the larger adoption of dynamic languages (PHP, Python, Ruby) for Web applications.
I have not tried but it must be possible to deploy your PHP applications with Quercus, OC4J and the Oracle database.