Like probably many of you I have been an Amazon associate for years. However, since their ads did not generate any revenue I kicked them off.
Now, for week or so, Amazon is offering ads that relate to the context of the site or blog where they appear. This beta-service Omakase (Japanese for "leave it up to us") has not been announced very loudly, but discussions on the blogosphere are slowly taking off.
My first reason to write this post: I'm now selling books, so the system actually seems to work.
Amazon's legal disclaimer warns against using Omakase together with Google Adsense: "Why? Because Google doesn't want you to use any other services that also dynamically scan and analyze the content of your individual pages to ascertain the best possible material to display. You might be able to get a waiver from them, but I would definitely discourage you from having both throughout your site and just hoping you don't get caught."
Webloggers like Dave Taylor have already checked with Google and they say from their perspective it is nonsense.
From my experience it might more be technical problems Amazon still has to solve in its beta-mode. Amazon ads at my site often show up as Google ads, suggesting that both tend to get mixed up. But it is not nice for Amazon to blame Google for problems that Amazon shares.