Jeff Weiss, a QA engineer in the Red Hat Cloud QE group, informed me that his group uses Clojure internally at Red Hat for automated testing. He said they used to use Java, but that Clojure offers several critical advantages that make developing automation much faster (and more pleasant).
At the moment, he is working on automated tests for Katello. The tests use an extended Selenium API and are composed using a Clojure API that wraps it. The codebase can be found on github:
Jeff put together a short screencast to demonstrate the benefits of composing the tests in Clojure.
I think there is a good opportunity here for collaboration w/ the Arquillian project...perhaps even to merge (or replace) their Extended Selenium project w/ Graphene and drive the tests via Drone.