I wrote some time ago about my search for the best programming language. Now I have discovered a new language that meets a lot of the demands: Clojure.
Clojure is very much like Lisp. It runs on a Java VM. Java VMs are stable and either already installed on many platforms or easily available. All the objects you can import into Java are available for calling from Clojure. The Clojure programs can be deployed as .jar files and no-one needs to know you actually produced it with a high-level functional language.
Clojure also has good support for multi-threading and it does it with a new and interesting way by implementing software-transactional-memory, which apparently makes thread programming easier than using locks.
It is licensed under the Eclipse license. IANAL but it looks to me like it would be possible to use it for commercial software development without any major problems.
I'm still reading the documentation and I haven't written anything more complicated than a hello-world with it, but I'm liking what I see so far.