Based on that page, I'd say Clojure is pretty well suited to scale over multiple machines. It's not an either/or thing; Erlang can work just as well on one machine as on ten. The point, though, is that something which can run on several machines at once is always more robust than something which can only run on several cores at once.

The downside to the share-nothing model (which, as you pointed out, Clojure uses) is that it potentially reduces the speed of communication between processes on the same system. I don't think this is a problem in most cases, but it is a consideration.