You could use Clojure today to write tests and scripts on top of the Java VM. While there are other Lisp languages implemented on the JVM, I think Clojure does the best job of integrating with Java.
There are times when the Java language itself gets in the way of writing tests for Java code (including "traditional commercial programming"). (I don't mean that as an indictment of Java -- other languages suffer from the same problem -- but it's a fact. Since the topic, not Java, I won't elaborate. Please feel free to start a new topic if someone wants to discuss it.) Clojure eliminates many of those hindrances.
