There was an article on this in the July issue of php|architect.
Have a look at either one of the following, or all:
Zend Server Community Edition. Install and then later on also enable the Zend Java Bridge extension.
Websphere sMash (project zero). Requires Java SE SDK, but I don't know what version.
Quercus & Google AppEngine. You will also need an up to date version of Jetty JAR and Jetty util JAR. Do note that PECL extension's won't work with this.