I think this would be best delivered as a gem too. Forking and pulling down a copy is a good start, but having this as a gem would make me smile.
(Just an FYI.. it doesn't seem to work on Ruby 1.9.2, though 1.8.7 was OK.)
Please send me a pull request if you're able to figure out what is going on :(
I didn't really have time to dig into it but.. I'll have a quick look for 5 minutes now anyway. I'm on 1.9.2 by default so might easily be able to see the problem.
UPDATE: Ok, you have a pull request now ;-) Got it working. Specs now pass.