A bit OT, but: checking popularity with indeed.com is a fishy thing. First there is a trend even for simple PHP-only shops to post ads with the phrase "Haskell, Lisp, Scala, Clojure knowledge is a pre" (Yes, the "beating the averages" effect reached recruting years ago)<p>Haskell as an example: Haskell County healthcare and the company Haskell & White and more like these are occupying the first three pages of haskell results before there is a Java dev ad using the "at least one of { Scala, Erlang, SML, Haskell, Prolog, Lisp, Clojure }" phrase.<p>Clojure: on the first page I count three real clojure jobs and seven "at least one of ..." mentionings.<p>For Scala the indeed search turns out to be more relevant.<p>Conclusion: Get out of my face with indeed.com, their data is next to unusable for PL connected job trends.
If Java itself were included in the poll, then a logarithmic scale would be required :-)<p>Personally, I really enjoy Clojure development, but Java is still the elephant in the room. Also, even though JRuby doesn't rate as high as the "big three," JRuby is incredible useful for merging work done in Ruby and Java, and for taking Ruby web apps and deploying them on the JVM.
Have they considered what the languages are being used for? Scala with its intensive static typing is more likely to be used for serious systems, while Groovy for quick scripts to test stuff. And then there's JRuby not mentioned, because its lumped under Ruby: who knows what proportion of that is JRuby and what is Matz's Ruby?
Interesting to see how three JVM languages have emerged from the pack. Scala and Groovy proving popular amongst Java developers. Clojure also with a substantial following, but less commercial adoption.