I feel the author of the story missed out on drawing some important business conclusions: 1) the lack of authentication of users makes tripadvisor vulnerable to a better product, 2) the fact that users have to sift through reviews or have a strategy to read reviews points to the fact that a more personalized service would be a great benefit to travel researchers, 3) people are craving information from people they are sure they can trust or who have the same tastes as them.

The ebay parallel is apt, since I think they're both at risk of the same thing: If you allow one of these "communities" to transform itself from a garage sale into a mall, the original value proposition is lost. Authenticity gets replaced by convenience as a reason to exist. And that, my friend, is much thinner ice out there on the internets.