My old MacBook Pro (A1260/MacBookPro4,1/OS X 10.5.8 Leopard) might be getting a little ragged at the edges, might be needing some new memory, but it can still play with the cool kids after fixing a couple of small issues getting Leiningen (both 1 and 2) to work.  In short, using Java 1.6 fixed the problem.

Download Leiningen in the (well, my) usual manner:

mkdir -p ~/local/bin
export PATH=~/local/bin:$PATH
# Leiningen 1 is currently "stable"
curl -k 'https://raw.github.com/technomancy/leiningen/stable/bin/lein' > ~/local/bin/lein1
# Leiningen 2 is "preview"
curl -k https://raw.github.com/technomancy/leiningen/preview/bin/lein > lein
chmod a+x ~/local/bin/lein*

Problem now is that lein doesn’t work: I was getting Caused by: java.lang.ClassNotFoundException: javax/tools/ToolProvider.

It looked like I was running Java 1.5:

$ java -version
java version "1.5.0_30"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0_30-b03-389-9M3425)
Java HotSpot(TM) Client VM (build 1.5.0_30-161, mixed mode, sharing)

Google searches turned up the info that indicated Java 1.6 was probably available, just not configured. Additionally, re-symlinking /System/Library/Frameworks/JavaVM.framework/Versions/CurrentJDK to 1.6 wasn’t enough for me, I also had to update Current:

$ cd /System/Library/Frameworks/JavaVM.framework/Versions
sudo rm Current
sudo ln -s 1.6 Current

Now, java -version was reporting 1.6, and lein was all happy.