One of the most interesting applications of running PHP on Java is that it enables you to run PHP on Google's Appengine (yeah, I know, if all you have is a hamer...)
See <a href="http://www.webdigi.co.uk/blog/2009/run-php-on-the-google-app-engine/" rel="nofollow">http://www.webdigi.co.uk/blog/2009/run-php-on-the-google-app...</a>
Someone runs wordpress on Appengine via Java: <a href="http://blog.caucho.com/?p=196" rel="nofollow">http://blog.caucho.com/?p=196</a>
Sounds like they intentionally ignored that PHP has connection pooling and FastCGI to reduce the overhead of spawning new connections and new processes. Looks more like a marketing pdf than a technical paper.