Finally some clever people cracked it and created an interactive TV app that gets a high viewer engagement. Interestingly (??) on an activity that is natural with the content: namely answering the questions on a knowledge quiz.
The participation is so high that the servers could not handle it any more. Some figures: around 2M viewers (out of 17M people total), 2M downloaded apps, 300k active users. Is this a breakthrough: probably not. But there is some value if the TV content is suited for user interaction. Will try it myself one of these days. Do read more in the article on Richard Kastelein’s website.