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Blogger offers several feeds for blog posts:
(1) blogname.blogspot.com/atom.xml - the old address for Blogger's ATOM feed
(2) blogname.blogspot.com/rss.xml - the address for Blogger's RSS feed
(3) blogname.blogspot.com/feeds/posts/default - the full feed
(4) blogname.blogspot.com/feeds/posts/summary - the summary feed
... but Blogger only remembered about the first one. The other three don't redirect to the new feed, which is pretty strange, considering that the feed #3 is new Blogger's default feed.
FeedBurner's blog notes that "by redirecting your feed, you can get a true picture of how many subscribers you have. Some of you might even see a few more subscribers magically appear, though results will most certainly vary."
Even if Blogger mostly introduced this feature for FeedBurner, you can redirect your feed to any other address (for example, to a feed that mixes posts from all of your blogs).
Last week, FeedBurner started to offer its premium services for free and it's pretty clear that, unlike other Google acquisitions, FeedBurner really moves fast.