I love Lisp, and find there is a lot to like about Clojure. But we're building a system with critical (life-or-death) high-reliability requirements, so we're going with Erlang for its proven robustness and scalability. Personally, I'm not thrilled with the Prolog-like language syntax, but there are alternatives in the making. Erlisp had promise, but now appears to be fallow, but Robert Virdig's Lisp Flavored Erlang (LFE) [
http://news.ycombinator.com/item?id=286288] looks to be progressing well. We're planning on switching over when it achieves a bit more maturity. Lisp on the Erlang VM - best of all worlds!
The only knock I'd have against Haskell is, even though the Haskell proggers I've been fortunate to meet are wizards, all have already involved with cool projects, and are reluctant to jump ship.