I do. Erlang is a blast. It's a language/platform specifically developed to be very scalable and very fault tolerant- because it was designed for telecommunications systems. Here's a nice write up from some of the guys at Sendmail: http://www.jetcafe.org/~npc/doc/euc00-sendmail.html

It's not a particularly popular language (I guess no functional language is)- and has only started gaining traction the last few years. Which means nothing of course. It's a bit of an oversimplification, but to me Erlang is to pi-calculus what Lisp is to lambda-calculus.