Paul Graham is one of the biggest advocates of using LISP for web development, and Clojure seems to be the most popular LISP for web development. In fact, since it emphasizes immutable data structures and parallelization, it's even supported by Heroku and will probably get more and more adopters.
I know Paul Graham believes Arc is or will ultimately be the most expressive LISP for web development, but he still writes about Scheme and Common Lisp. I cannot find anything on Google where he discusses his views on Clojure.
So what are they?
We're trying to make something for the long term in Arc, something that will be useful to people in, say, 100 years. (If that sounds crazy, remember that we're already up to 50.) So (a) we're not in a hurry to save effort; when you're trying to make something that will last 100 years, there is plenty of time to work on it, and (b) we don't want to adhere to anything that isn't timeless, lest the whole project curl up like a bimetallic strip. (http://paulgraham.com/arcfaq.html)
If I read it correctly, according to pg JVM isn't timeless, and Clojure is at risk of curling up like a bimetallic strip. :) (For the record, I believe Rich Hickey is a genius and his recently released Datomic is ground-breaking. Clojure is pretty good too, but just a trite top heavy with Java/JVM.)