I think that this just the beginning for Teevox. When I met the founders last spring they were showing off a prototype iPad app that was sort of like a live newsfeed for television. As you watched a show it would pop up additional information about what was going on at that moment, like who the actors were, what song was playing in the background, trivia, and I'm sure in the future targeted ads.

I think the integration with Twitter and Facebook also indicates that they're going to be building some social features into the app, which would be pretty interesting to see. Anyway, definitely keep an eye out for these guys.