(A live version with more than one repo can be seen here.)
So far this badge works with Firefox, Safari 3.x and Opera. I haven’t had the resources or motivation to make it work on IE though.
If you want to use it on your website you should just download everything from Github and put it on your webspace. The README shows you how to embed it into your webpage (I made sure that the CSS-elements don’t clash with your existing stylesheets).
If you want to contribute to it you’re welcome to (the easiest way is forking the repo at Github), but please don’t try to make it into a monster-app which does much more than it was intended to do.
Update: I notified defunkt of GitHub and what do you know, I got featured on their blog (entry here). Awesome. I hope I can put some further touches into the project in the next few days.