The score's based on your use of GitHub, who follows you and your projects, as well as (this is where BackType comes in) how much they are shared on Twitter, Facebook, Reddit, Hacker News, etc.
didn't load for me; you should throw up an example screenshot of what the score looks like. have you thought about making an embeddable score widget (similar to what ohloh has) that you could put on a blog?
Since we're using BackType as well to calculate the score, it was easier to do both requests server-side. We pre-ran a long list of popular users and all of their followers, but guess we didn't reach enough people :(
How is this score calculated?