This is called an “Unwind Segue“. Unfortunately there’s no documentation for this so far except a brief mention on XCode 4.5 new features list that states:
Unwind segues can allow transitioning to existing instances of scenes
in a storyboard
The good news is that there is a session from WWDC 2012 explaining those creatures (among other things).
You can just login to Apple’s iOS Dev Center with your developer account details and then go to the WWDC 2012 videos page and watch “Adopting Storyboard in your App” (it’s fifth from the top) The discussion of unwind segues starts at time 37:20.
Update:
Here is some more info on the subject from Apple’s documentation
A placeholder object named Exit for unwinding seques. By default, when
a user dismisses a child scene, the view controller for that scene
unwinds (or returns) to the parent scene—that is the scene that
originally transitioned to the child scene. However, the Exit object
enables a view controller to unwind to an arbitrary scene.
(From iOS6 docset > General > Getting Started)
And here is a nice example of how you can implement one
Another Update:
Here is a technical note from Apple regarding this topic.