It was during the Virtual Tech Days when I was presenting the "Exception Handling In WCF" session, one attendee wanted on how to use the fault reason to have multilingual / multicultural exceptions being handled and shown without any extra code. And so I promised him to post an article on the same and here it is now

http://www.jebarson.info/1/post/2010/11/multi-language-multicultural-exception-handling-in-wcf-using-faultreason.html

Also check the sample there.