Google App Engine accepts Java bytecode and even supports run time loading of bytecode. http://googleappengine.blogspot.com/2009/04/many-languages-and-in-runti

Google App Engine accepts Java bytecode and even supports run time loading of bytecode. http://googleappengine.blogspot.com/2009/04/many-languages-and-in-runtime-bind-them.html http://googleappengine.blogspot.com/2009/04/many-languages-a... So even though there are limitations (e.g., single thread), the following languages can run on App Engine through the Java back door: PHP, Clojure, Groovy, JavaScript, Python, Ruby, Scala, Scheme, Beanshell, ... Here's a wiki page with some info: http://groups.google.com/group/google-appengine-java/web/will-it-play-in-app-engine http://groups.google.com/group/google-appengine-java/web/wil... Also note that it's possible to run multiple languages against one datastore by using the built-in versioning system.