The collective sieve known as Valleywag deliberately filtered out the me-too launch, earlier this month, of Amazon.com's Clickriver, a targeted advertising system that places what are essentially sponsored search results into Amazon's product listings. Say you're shopping for an MP3 player ... "Well look there, maybe I should buy a Zune." Predictable, and Amazon has long carried ads in its listings, and Clickriver just appeared to be a self-service interface for buying these ads online. But then we happened to stumble across a listing for the Amazon online display advertising team.