Although the majority of the documentation talks about the release of Java for Appengine, there’s an important distinction to make…they reallly released the JVM for Appengine, as evidenced by this nice post about which JVM languages will work on Appengine.

So, really, in one swoop, they released Jython, JRuby, Scala, Javascript, and Clojure. That’s pretty slick.

Sure Java is arguably way less nice than Python and Ruby, but the JVM is pretty great. Languages that target it as a platform open up a lot of otherwise closed Enterprise doors. If you want to write Python or Ruby as your day-job, you should really start paying attention to the JVM.