This is the paradox - most of the time people do not know exactly what they are looking for - but most of the time the do know what they are looking for when they are looking to buy something. And that is where most of the money is.
And the reason why product-related search isn't better is because most of the data out there is hard to get. You basically have to screen-scrape, which is hard. Unless you are google and you can get everyone to send you a feed...
Link: John Battelle's Searchblog: Scoble Suggests The Search Chapter 13.
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