The link to the full story is here
The following changes can be enabled/disabled using the "March 2013 Breaking Changes" migration until March 6th when they will go into effect permanently for everyone:
No more accessing mailbox FQL tables without a user session
It will not longer be possible to access the message, thread, or mailbox_folder FQL tables without a user session.
Removing apps from /me/accounts/
We will no longer show apps under /me/accounts/ in the Graph API. You can access the list of apps a user is a developer on by hitting /me/applications/developer/.
Removing redirect to docs when hitting graph.facebook.com
We will no longer return a redirect to the Graph API docs when hitting the URL http(s)://graph.facebook.com with no path.