Google announced on a blog post, and amoung many other announcements that it will start retiring Adsense for Feeds on 2 October, and by December 3 there will be no more earnings from Adsense for Feeds.
Adsense for Feeds was essintially a service from Google AdSense to put adsense code and monetize blog or webside feed beside conventional ad units on this site.
Althought revenue from this service was very little compared to adsense ad units, many webmasters think it was a good way to monetize feeds ayway.
On official Google blog post also it announces merging of Google insights and Trends, Google +1 reports to webmasters and more.
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