The Google AdSense for Feeds (aka FeedBurner) blog announced that all of their links will be 301 redirected, as opposed to some that are 301 redirected. In summary, when you use FeedBurner to create and host your RSS feed, FeedBurner creates special links that are used to send the reader to your web site. Some users selected to use a 302 redirected link, as opposed to a 301 redirected link, to obtain better tracking.
Google has made the decision to remove the 302 redirect option and make them all 301s. Why? The main reason is Google wants these URLs to become “more compatible with search engines that crawl feeds.” A 301 redirect is the best solution for a search engine to determine where a URL lives. 302 redirects historically have confused search engines, as well as webmasters. So to be “consistent with the way that content is distributed today,” Google has made this change.
If you run FeedBurrner for your web site feeds, you don’t have to make any changes. Google has already made the 301 change for you.