That's great. Now, for the hacker-angle on the piece: How do I use this to do something useful in way that's smarter than how I'd do it in Python or Java?

And no, I don't consider an algorithm to calculate a Fibonacci sequence particularly useful.

Use agents (http://clojure.org/agents) and write an implementation of a ray tracer that uses many cores.

there are plenty of additional articles out there that you can find easy enough that talk about the advantages of functional programming and immutable data.

That's a fairly old article, but I think it's a pretty good introduction to get your feet in Clojure wet if you don't have a Lisp background (at least, it was useful to me).

I also bought the Programming Clojure book from Pragprog last night. Would anyone be interested in a review? (once I read it)

Isn't it early for a review? http://www.pragprog.com/titles/shcloj/programming-clojure seems to indicate that the book is still "in beta".

Yes, it is in beta, but afaik it's also the only book about Clojure available and I could not find any meaningful discussions (or even synopses) about it before I bought.

Supposedly the final version is due in May anyways and I can always update my review since I'll get access to the final book for free once it's out.

Please do!