Amazon have launched PPC ads for Amazon.com. The new program is named Clickriver Ads and is powered by their A9.com. “What is Clickriver Ads? Clickriver Ads is an advertising program — currently in beta — that allows businesses to place sponsored links on Amazon.com®, next to search results and on product detail pages. Clickriver Ads presents a unique opportunity to advertise services and products that complement the selection on Amazon.com, an online marketplace with tens of millions of active customer accounts.”
Amazon is using the same “bid + performance” model which was popularized by Google and will be utilized by Yahoo! as well.