If one is planning to create a UI-less web service (receives JSON and/or XML, returns JSON and/or XML), does Noir provide anything useful over and above Compojure?
I believe Noir makes it a bit simpler to create JSON responses with noir.response/json
: http://ibdknox.github.com/noir/noir.response-api.html#noir.response/json
On the other hand JSON support in Noir is just a very thin wrapper around clj-json (basically only adds json content-type header) so you can use clj-json directly instead of Noir for this purpose.