We also have ClojureScript, which is basically Clojure that compiles to Javascript: Lisp for the web browser. It combines the power of Clojure with Google's Closure web development library to spit out tight Javascript without any of the bad parts.
It's still not fully baked, but it's getting there. Clojure Lisp for web client development on top of Clojure on the desktop and server - my cup of Lisp doth brimmeth over.
I looked at ClojureScript at the source and perhaps I am wrong, but I like the simplicity of Arc and his approach.
But it is fine that others also go into this direction.
I think the difference is that to run an Arc powered website, you would need an Arc box on the server side, which is what you would need for running Clojure websites as well. What ClojureScript does is generate and compile the necessary JavaScript which can be off-loaded onto any (or at least most) web hosting sites, including shared web hosts. Additionally, the use of compiled JavaScript gives you the benefit of leveraging client-side processing, as opposed to Arc or Clojure boxes which are server-side solutions.
But you are right, Arc is great too, and it ultimately boils down to individual choice. Arc is my first Lisp, and I like it above Scheme/Common Lisp, as well as Python and Ruby.
