"When you enable autodiscovery for your rss feed it allows browsers and aggregators to automatically detect the RSS feed when your browsing, and it makes it easy for the user to subscribe to it."I just bumped into the feed autodiscovery issue yesterday.
Wordpress, Blogger and TypePad are setup by default to autodiscover their inbuilt feeds.
So if you use a Feedburner feed, you've got to change your code, as noted above, to point to the Feedburner feed instead of the blog's fdefault feed.
REDIRECTING YOUR RSS FEED
Once you do that, you should also redirect those that have already subscribed to the inbuilt feed to switch over to Feedburner
I figured out how to do it for WordPress by adding some code to my .htaccess file. They are talking about redirecting your Feedburner feed over on the Feedburner forum.
There also a Wordpress Feedburner Plugin for this.
I don't even know yet if I can add the redirect on hosted sites like TypePad or Blogger.