Do you know anything about how BackerKit works? It seems like it's API connected but I'm positive there's no public Kickstarter API.
It's kind of messy, but frankly ingenious considering there's no alternatives.
One of BackerKit's founders is/was involved with Diaspora, which was a Kickstarter project. Having the Kickstarter project admin interface (with actual backers) handy to develop and test the bookmarklet against was probably quite a boon. I could be wrong, though.
tl;dr Kickstarter really needs an API.