According to Microsoft's Ben Kilgore, "One of things that we haven't talked about is the way the saved game architecture works. It's more like a phone a little bit. So you are not going to lose your save game stuff as you are switching between tasks."
It is not intended as a save game - rather, it will allow gamers to simply take a break from the console and come back to the game where it left off.
The Xbox One also features a universal pause. Simply speaking "Xbox, pause" will freeze the Xbox One til the user states "Xbox, on."
The PlayStation 4 will have a similar feature as well.