Blogger Feeds as Sitemaps with FeedBurner (and Google Webmaster Tools)

...if you have a site whose original feed redirects traffic to FeedBurner (for example, if you use Blogger redirection, or you use our FeedSmith plugin for WordPress), you will need to give Webmaster Tools the address of a feed that does not get redirected as a sitemap source.

For Blogger users, the following general feed URL format should always work:

http://mybloggerblog.blogspot.com/feeds/posts/default?redirect=false

For WordPress FeedSmith plugin users, use this URL format:

http://www.mywpblog.com/?feed=rss2

For other platforms, other feed URL variations that are not redirected are what you need to provide.

(from FeedBurner Forums).