Many might consider even the thought of running PHP inside of a Java Virtual Machine to be anathema. Others will wonder why bother (apart from the novelty). However running PHP in Java has one crucal benefit: it future-proofs your code.
Quercus is a nifty utility that will allow you to run PHP code in clouds such as Google App Engine1. This means your Drupal and WordPress sites can now be distributed across a highly avaliable and scalable cloud infrustructure.