This doesn't appear to be using Hiccup, which is a shame. But the bigger problem is that the JVM/clojure start time. Rich Hickey has even said that Clojure isn't right for scripting.
You could create a nice Clojure static site generator in ClojureScript (using Himera to compile the templates) though.
That sounds completely counter-intuitive to me. A static site generator is run once you add something to your site, i.e. not that often. So a slight hit in startup speed isn't really a factor, whereas runtime efficiency is (dependencies are hard, so most SSG's out there recreate the whole site for each new post/page).
I gotta agree on that, the only reason for needing a fast start up time is if you want to rebuild after every change and see the result, but misaki actually watches for changes while it's running.
An extra second or two on start up really doesn't matter one bit.
Honestly, why? Considering the rather insane amount of time something like jekyll needs, a few seconds don't matter at all. So having a background service won't really get you anything for "production" usage – even if you'd be doing twitter-like 20+ items/day micro-blogging. The only gain I could imagine from a setup like this would be prototyping the look and feel of your site in its very early stage, where it would save you from half a dozen script invocations.
Those seconds would only matter if they would be a large percentage of the whole running time. And I've yet to see a SSG where two, three seconds for a year or more worth of blogging would actually matter.
Is this just for people who have a JVM, but don't have ruby on their box, or are there significant advantages other than just the programming language and environment?
I consider the idea (didn't proceed further than reading the project site on Github yet) great, because - yes ruby is something I don't usually install. Dependencies that are useless for me except to host X are not a no-go on their own, but are counted as minus points.
That and the fact that it's neat to be able to extend the software you're using. I just don't know ruby and the culture is alien to me (running redmine and gitorious for my company - from configuration to error messages).
No hate against ruby. Just a preference for something else.
You could create a nice Clojure static site generator in ClojureScript (using Himera to compile the templates) though.