This is sweet. Too bad I don't know rails...it's on my todo list though. Would love to get this same functionality setup for my site, nicestperson.com but sadly this is written in PHP (which apparently was the language that cave men coded in). I love the name auto fill functionality too. Works really fast. Great job!
Facebook has an SDK written in PHP so you should be able to work with that. It's pretty simple if you follow the examples. As of yet there is no official SDK for Ruby though the unofficial implementations are pretty decent and easy to work with.
I have used the Koala gem recently for working with Facebook's Graph API and I am a huge fan.