The growth of Clojure has been exponential both among users and clients. A few years ago nobody could have imagined that a Lisp would have such rapid uptake, but it seems that the combination of a solid product, great libraries (JVM) and a productive community was all it took.
IIRC the Google Group is now in excess of 3000 members and if you'd like to try it out I suggest you follow it or join us in #clojure on irc.freenode.net - If you're a professional developer it'll be worth your time, if not you'll at least have some fun!