Social TV

There are a few out there already, social media web site of some kind sharing comments on the TV programme your watching right now.

A full feature set might include the usual tablet and smartphone apps too, along with rating of the story line (a bit like the rating of the speeches given during elections) or following at social trends and watch what "they" watch.

A more fancy feature set might include influencing the TV program story line via social media or maybe even the actor/actress interacting via social media with the audience (while on TV) either live or staged.

Pretty sure this has been thought off already, so how to make it happen?