We are hearing reports that Google has opened up the AdSense for Feeds Google product to more AdSense publishers. A Google Blogoscoped Forums thread and a WebmasterWorld thread has several publishers noticing the new option.
Personally, I thought AdSense for Feeds was open to all by now, but I guess I was wrong. We were one of the first sites to ever deploy AdSense in our feeds. Back in May 2005 Google announced the beta of AdSense for Feeds. We were approved for the beta the same day and started to immediately experiment with those AdSense for Feeds option.
Yahoo has been beta testing publisher network ads in feeds since September 2005, we gave them a try in November of that year and then removed them in January 2006. Since then I have been using FeedBurner's ads. But now that FeedBurner stopped accepting new publishers and income is down, I might pursue other ad models.
If you want to see a screen capture of the current options for setting up AdSense for Feeds in Google, click here.
Update: Confirmed, Google has an official post over here on the matter.