Interesting project. Not sure what prompted the posting now (last updated in April), but it's timely for me, as I'm evaluating lightweight JVM-based languages. Jython seems a bit heavy. Clojure is my likely choice, but I'll take a look at this too.

FWIW, a quick run of the binarytree benchmark shows luaj as slightly faster than luajit on my system, but does it matter? Not many projects have a realistic choice between lua/luajit and luaj, unless the whole thing is written in Lua.