As great at this probably is, I don't think adding yet another dependency to facebook is a good thing.

I'm getting tired of services that only accept facebook users. Having a facebook login or any other facebook service requiring the user to be a facebook user is not bad in itself (and can be pretty useful), but it should _always_ have an alternative.

That's why I think projects like Dial2Verify Twilio are a great thing. They're still not perfect though, as some said here on HN.