I work in a very large company that has primarily Java for web apps and back end processes in COBOL/Mainframe environments. I've been steering things towards Groovy or Ruby for new projects, largely using productivity as the justification. Top push backs from upper management have been: 1) Universities we recruit from teach Java & most prospective employees already know Java 2) Costs of retraining workforce 3) They don't understand those langs can be utilized with our current JVM ecosystem

I feel pretty much all those reasons are specious and really shouldn't be holding things back. We've got a foothold established with success of some smaller projects using Groovy and Ruby to "prove" their viability. I'd like to try Scala next to see how it would fit for some of our other projects.

TLDR: At least one large company is making efforts to evolve beyond just Java in the JVM.

"IMHO Java's success today is more because of corporate inertia than anything else."

I don't think so. Java as a platform is a lot easier to manage than most other platforms, including Ruby and Python. Jars, in my experience, are much easier to deal with than Gems. Java has a set of advantages that aren't really replicated elsewhere. It's garbage collected and portable, but executes much faster than other garbage collected and portable languages.