It's not just Scala, it's Groovy, BeanShell, Factor (JFactor now), Fantom, Frege, Kotlin, Ceylon, Stab, Gosu, Mirah, and that's not counting all the ported versions of Ruby, Python, Lisp (Clojure) and so on.

What you haven't written a JVM language yet? It used to be you weren't a proper programmer until you'd gotten fed up and written your own CMS or web framework. Now I guess everyone has to have their own programming language.