The AdSense ads inside FeedBurner RSS feeds will be contextual and CPM based - i.e., you get paid based on the number of ad impression - so the more subscribers you have, the more revenue.
And most likely you’ll see image banners in the feeds, not the regular text ads. THe RSS ads can be managed via the regular AdSense dashboard.
Google will initially experiment with only a small group of AdSense publishers but will eventually roll-out the program to all AdSense and FeedBurner customers. The layout will be quite different from the earlier screenshots.