By Joshua Eichorn
I found an interesting project, quercus that compiles PHP to Java Bytecode allowing it to run ontop of the Java Resin Application Server. It has a couple neat features, one being PHP6 compatible unicode support, the other being easy integration between Java and PHP code.
It also seems to perform well, implements a large part of the PHP api, and lets you implement anything your missing just be writing a new Java Class.
It will be interesting to see if a project like this can actually take off.