which makes me wonder if there is a simple java package to do that - probably not much to write a simple curl / wget for java so that on any machine with a JVM you can just lein your way to clojure...

I am using Windows more these days, because of work. I will start documenting what I have done to make Clojure and leiningen work properly, and see what can be contributed.

Which is fair. I don't use Windows a lot myself — this is basically the "League of Legends and Sims 3 machine." I was just pointing it out because lein.bat was mentioned, and I found it kind of surprising given how easy Leiningen is on other platforms.