FaKod (I think that translates as "The Fatalistic Coder"?) has written a nice Scala implementation of the Circuit Breaker pattern, and even better, has made it available on GitHub.

Check out http://github.com/FaKod/Circuit-Breaker-for-Scala for the code.

The Circuit Breaker can be mixed in to any type. See http://wiki.github.com/FaKod/Circuit-Breaker-for-Scala/ for an example of usage.