If this post from ComparisonEngines.com is correct, Amazon is launching something big -- ProductAds. Instead of trying to capture all ecommerce transactions on the Amazon.com platform or marketplace, Amazon is now referring transactions to other non-Amazon merchants. Basically, Amazon.com is becoming a comparison shopping engine.
Perhaps this is a result from Amazon's recognition that "the percentage of shoppers who started at Amazon has continued to fall, while the percentage of consumers who say they start shopping at a search portal has risen." Given that ecommerce search represents a big portion of Google's Adwords revenue -- and almost 100% of eBay's revenue -- if this takes off, it could have a pretty big impact on the ecommerce world.