The whole thing might sound ludicrous. On the other hand, this is precisely (precisely!) how Facebook works.
While you have conversations with your friends, Facebook "listens" (in the parlance of this hoax) and presents you with contextual ads based on what you've said. Mention your engagement and you'll be shown engagement gear. Mention your interest in basketball and you could be shown jerseys.
What's fascinating about Hearscreen is that it is not only plausible, but predictable. The things which had held it back were:
1) the TV-microphone install base, which is coming
2) Reliable voice processing, which you may have heard is now coming installed in just about every phone and
3) an ad market to develop to buy and sell these kinds of contextual ads.
The last thing is the toughest part, but it's also what Google and Facebook specialize in, and you know they want to and will be on and in your television.
Add all that up and the Hearscreen concept -- contextual advertising based on real-life conversations you're having -- will happen. Something like this technology will come to market in the next five years. And if you have privacy concerns, they'll just say, "Hey, you've been doing this same thing on Facebook for 10 years!" And they will be right.
Which is another good reminder that the norms that we're establishing in the online world will eventually interact with the norms you expect in your physical space.