Amazon.com launches contextual ad service

It’s still in beta, but Amazon.com has launched a new contextual advertising program for its Amazon Associates.

Unlike AdSense, this program will comb your content for relevant text and link it to products in Amazon.com’s inventory. If a site also has Amazon’s preview enabled, users will see a little product flyover when moving their mouse over the link. See an example at Thought Garage. Other companies offer a similar service, but none (to my knowledge) have as big a brand as Amazon.com and none offer their own products for sale.

I’m always happy to have another way to monetize my content, but I’m leery about how it will affect user experience and site credibility. What are your thoughts on this type of advertising and/or Amazon’s (second) foray into Google’s territory?