Im not sure if anyone's noticed or written about this yet but the Twitter option in feedburner [webmasterworld.com] has gone awol. In fact the entire "socialize" option link now appears missing.
The service is still active(for now), you can manually navigate to the socialize page by typing the address in your navigation bar. old address: feedburner.google.com/fb/a/socialize?id=YOURIDHERE
What I liked about the service was that it automatically used Google's shortening service for links which comes with analytics. At this point the service is still active though unreachable if you don't know the address so it may be taken offline, eventually, or perhaps it will just stop accepting NEW connections but will not change existing connections, or?
Perhaps Google simply decided to stop promoting twitter altogether after their fallout over tweet indexing. Who knows.
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.