Groovy is different because it's easy for Java programmers to learn. In fact, most Java devs can understand Groovy code with little or no explanation. That's certainly not the case for JRuby or Jython. In any event, I agree Clojure is pretty sweet. However, being a Lisp, it's future is questionable. A lot of devs won't be willing to deal with the brain melting process necessary to grock it.
Yeah I agree with you there. I do use groovy as my "java and then some" language. It looks an awful lot like ruby to me, but yes it's more java-like.
Its unfortunate about lisp(s) and their popularily, because honestly I don't see what's so difficult about them. Macros are hard, but lisps don't force you to use them. Other languages don't even give you an option, you can't. Paren matching is done by any modern editor. Prefix notation is a bit unintuitive I guess, but that slowed me down for maybe a couple of weeks, about the same as new syntax for almost any language. I am starting to think that "a lot of devs" just don't want to understand it. Or maybe a lot of devs just don't get programming in general, they just learn their one language, and can maybe pick up a few similar ones.