This means you can grab a copy of it and run your own album art badge service in just a few minutes.
I've been asked regularily over the past few years (this service is over 3 years old already) but I never wanted anybody to see it as the code was in really bad shape. A year ago I decided to rewrite everything but still didn't feel too comfortable publishing it. That's officially over now (although I still don't like the code too much).
If you're any good at PHP go ahead, fork it and hack away at your own will. Also pull requests are welcome anytime.
Also don't worry, I don't plan to close this service in the near future.