How important are recommender systems?

Tom Slee thinks that recommender systems are the wave of the future. The prototypical example of these is Netflix, where you are alerted to movies that the algorithm thinks you will enjoy based on your vote history. He makes some interesting points about transparency in these systems:

Transparency matters. The unmarked presence of sponsored items in a recommendation list would be widely viewed as a corrupt set of recommendations, but just as bookstores charge for premium display sites within the store, so sites of recommendation lists may be sold. Recommendees have a right to know if payola is part of the system.

In recommender systems, transparency is crucial because otherwise people will think that your opinion has been bought. In a pure rating system, however, you can't have transparency because that would make it easier for firms to game the system and watch their product climb to the top. I am not as optimistic as he is about the future of recommender systems, although I am happy to be proven wrong.