I think that the general idea is that many companies that employ ruby based technologies have been making a switch away from them. The reason is simply scale, it's not a matter of "oh java's the new thing because everyone's switching back to it" Java has always been there and it will be around for a long time. People are just now realizing what a great platform the JVM is and since languages like Scala, Clojure and Groovy exist on-top of the JVM it allows large complex systems to be created in a language agnostic manner because they will all run on the same platform. Interop between other languages and java on the JVM aren't always nice but the fact that it's possible lets you leverage the many java resources that exist. For example SummingBird https://blog.twitter.com/2013/streaming-mapreduce-with-summi... . SummingBird is a Scala platform built on top of Storm (a Clojure based real time computation system) and Scalding (a Scala adaption of Cascading (a Java library) which is used for writing map-reduce jobs easily) and they work beautifully together. So in my opinion their switch to the JVM and embracing of it was a smart move.