Sgt_Kickaxe - 6:25 am on Mar 12, 2012 (gmt 0)
I'm not sure how long it's been gone but there is something else, a pretty significant something else if you ask me.
The service changed how it handles links for existing users!(without telling users?)
Before: Feedburner would update twitter and 301 redirect the article link through goo.gl shortening service. The result was Twitter>goo.gl>YOURSITE.
Now: Feedburner still updates twitter and the redirect chain still passes through goo.gl but the feedburner page has been thrown into the mix! the result is Twitter>feedburner>goo.gl>YOURSITE.
You can confirm this by visiting goo.gl and seeing that all the links displayed under "long url" are feedburner.com and not YOURSITE anymore.
Why does Google need a copy of your pages on feedburner to begin with? Some of these pages are even being indexed - search for site:feeds2.feedburner.com for a list of sites that are 100% copied onto feedburner.