1) The attentional economy is more an observation about the state of the world than a "thing".

2) You can get free access to wifi at Boston's Logan airport in exchange for watching an ad (in fact i did just a couple of days ago)

3) Content creators are aware now more than ever that they're not competing solely with other people in their industries for attention. To that extent there is an effort to reach viewers/consumers/users on the users terms.

In short, i think it was incorrect to formulate the attentional economy as an actual thing with literal market places. The observations that've come out of it are still relevant and useful.

I think going back in time and explaining social networking to an audience would be tougher than it sounds.

It's pretty neat, and will allow all sorts of machines and devices to be connected to the web.

It certainly seems possible that in a few years Berners-Lee's vision could become a reality.