Ross Mayfield pulls together more evidence that displacement of viewing time by new media is well underway. Though - as I point out below, newspapers are the most overpriced advertising medium, the evidence suggests that all exposure based advertising models are under attack, both by direct competition and through the increasingly visible failure of exposure metrics to actually represent the value derived from advertising.
As both Ross and Jeff Jarvis have discussed, we're in need of both metrics and mechanisms to transplant some of this value and cash flow into new media. Doing so in a way that maintains usability and respects the privacy of viewers is a worthy design and business challenge.
But, I'm going to call foul on Ross' handwaving citation of Reed's Law as an antidote to Sarnoff's broadcasting formulations. Let's get one thing straight: Reed's Law is obviously, trivially, and blatantly false. It posits that the utility of a (human) network always grows as its membership grows. In fact, the utility is not just O(N^2), but is instead O(2^N). Umm, hello? If there aren't any negative terms here, then all groups naturally grow without bounds. That obviously flies in the face of both common experience and common sense. There is a conserved item in this game - time and attention. That's the basis of competition between old and new media, and among new media forms. A 'Law' that can't even model that fact is a bit of a waste, IMO. Try again.