I dislike re-writing code that works well without a very good reason. Sometimes there is a temptation to rewrite code in order to move to a new language and platform. The Quercus PHP run time WAR file from Caucho looks like a good way to mix and match existing server side Java and PHP projects. Several years ago, a customer asked me to loosely integrate (just share a common login) SugarCRM and the JSP+POJO+Prevayler based web app that I had written for them to manage their research papers and devliverables. Not difficult to do, but my integration solution was a hack. Compiling PHP to byte code for the Java platform and easier (non-web service) calls between PHP and Java is an obvious win for developers. When JRuby's performance gets better (and it will :-) I look forward to the same type of integration with both Ruby and Rails.