InfoQ: Clojure and Rails - the Secret Sauce Behind FlightCaster
http://www.infoq.com/articles/flightcaster-clojure-rails

Clojure is a LISP for the JVM created by Rich Hickey.

FlightCaster, a realtime flight delay site, is built on Clojure and Hadoop for the statistical analysis. The web frontend is built with Ruby on Rails and hosted on Heroku. We talked to Bradford Cross about Clojure, functional programming and tips for OOP developers interested in making the jump.

Another critical piece of infrastructure is Cascading; an excellent layer on top of Hadoop that adds additional abstraction and functionality. We definitely recommend Cascading to anyone doing serious data processing and mining with Hadoop.