On the logout page for each Stack Exchange site, there is currently a button for Log Out, which logs the current session out of the current site, and a button for Log Out Everywhere, which logs all sessions out of the current site. Would it be possible for there to be a Log Out of All Sites, to log out the current session across the entire Stack Exchange network wherever the user has a linked account logged in? I sometimes work on several SE sites at once, and it's a pain to have to log out of each one individually, especially since you get logged right back in by the auto-login across sites feature if you go back to a site you've already logged out of if you're still logged in elsewhere. One click to log out of every SE site currently logged into at once would be very helpful.
Clicking "log out everywhere" clears HTML5 local storage and prevents that auto-login from happening.
it does not, and cannot, log you out across domains. Otherwise I could somehow magically log you out of facebook.com from stackoverflow.com.
edit: The buttons on this page were simplified to just Log Out, which tries to log you out in every way it can. And if you have Stack Exchange credentials the Log Out button will indeed log you out everywhere, network-wide, by redirecting you to a special network-level logout page.