I'll probably get voted down, but meh. Congrats, Apple finally filed a patent that deserves to be granted. Most other power systems continue to draw current from the plug to run the detection circuitry they're talking about. That isn't new, making it battery powered is. And truthfully, some part of me does hope they start bragging about this, because the never of "powered off devices" which don't actually go into a low power state is disgusting. I'm looking at you comcast with your damn decoder boxes (not dvr enabled).
I will admit that for a properly created device, it won't actually save any power seeing that what's out there now pulls the power straight from the wall, while apples will pull from a battery, and then pull additional power while on to charge said battery, but meh.
Also, am I the only one that thinks that the extra battery is just another thing to go bad that you'll have to pay apple to replace? Seriously, most devices don't shut off, but go into low power mode so you can turn them on with a remote or similar, if this battery goes bad, you won't be able to turn it on short of a switch on the box. And at that point, you might as well create a zero power PSU by simply putting a hard switch which physically disconnects the PSU from power like a light switch does.