I didn't really see this article as being interesting from the "oh look, a reddit!" angle. I thought it was a good article in that it showed how to do a lot of things in Clojure: Java interop, a basic Compojure use case, and deployment with Leinengen.

How would you attack the "query performance, cacheing, scaling, etc" problems?

http://www.avc.com/a_vc/2009/03/thats-only-ten-lines-of-code...

Sure, you can replicate lots of sites but to me Reddit wasn't great because of the tech, it was because they had built something really zeitgeisty that people liked.