Thought provoking as usual, Brad. And while I know that you are far smarter than I, I remain skeptical that any near term technology can solve the implicit web problem.

And its for the same reason that Cuil, Powerset, et al will never challenge Google. While semantic/natural language search is far superior to keyword/Boolean search in theory, in practice the technology does not work effectively at web scale. Similarly, I do not believe that any horizontal algorithm can find what I am looking for without my intervention (i.e. the kinds of semantic content discovery companies that debuted at the recent DEMO).

I think many would agree that the leading practicitioner of the implicit web to date is @Gabe, and Techmeme is not only vertically oriented but I found it very telling that he recently added a human/editorial function. And I believe that there will not be any algorithm or technology that can solve this problem by itself in the short or medium term.

I think both vertical focus and editorial intervention will be required for any real adoption. $.02