Just read the notification from Google Adsense this morning:
Starting December 3, 2012, we’ll discontinue serving ads via AdSense for feeds on RSS feeds and you’ll no longer see feed units in your My ads tab.
For me since I last checked, feeds were not bringing me as much compared to my space here. I suppose Google Adsense may have found similar scenarios with others.
Or, maybe we can expect something new. Who knows. 😉