They've got libraries for Ruby, Python, and even PHP, and the interface is drop-dead simple. Definitely worth a look - I'm baking them into one of my projects right now.
This is amazing. Some years ago, I wanted to build a site that did essentially the same thing (but for a different issue), and this API either didn't exist or wasn't complete/accurate enough. It's remarkable how much power the web has to effect political change - seems like we're only seeing the beginning of it.
...that is, unless SOPA passes, in which case this may be as good as it gets....