How could a charger "cut out" when charging is complete?
It's pretty easy to make a charger that completely switches off any connections to the cell phone, so no more power goes into the cell phone.

However, most such systems still have a small amount of "standby" power trickling through the charger itself.

By "cuts out", I'm pretty sure they mean that (practically) no power comes out of the wall into the charger -- power is cut off to the charger and the cell phone, not just cut off to the cell phone.

The closest I've seen so far to a circuit that completely turns itself off is Roman Black's Zero-power PIC self-switch.