Since it launched with Apple's tablet in early April, the ABC app has 609,000 downloads and 2.1 million episode starts. "That's a significant amount of viewership since launch," said Albert Cheng, exec VP-digital media for Disney ABC Television Group. "For us, it's additional distribution and additional inventory, but the inventory is an incredible premium experience.

I think the jury is still out regarding the advertising value of TV apps. The problem is there's now so much TV inventory with broadcast + cable + online. Adding mobile apps to the mix only creates more supply. As an industry, maybe we ought to focus on increasing demand and actually limiting supply. 

That doesn't mean limiting viewer access to content on different devices.  It means being more selective about what inventory is made available to advertisers, and how to best package it.  It also means capturing more value back from viewers, via subscriptions and non-free apps.  Give users a super-compelling experience via a TV app, and they will pay a few to several bucks for it. 

That may be the full revenue value of apps.  But building that direct relationship with viewers is priceless.