Quote Originally Posted by treony View Post
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The touchstone has to be touching the phone at the special contact points provided by the separate battery cover...
The Touchstone DOES NOT need to be touching the phone. But, since the anti-gravity option is so expensive they have chosen to just rest the phone on top of the Touchstone, so yes they will be touching, and since the top is sloped they have installed magnets to hold it in place.

The special back will contain an inductive loop to pickup the magnetic field generated by the Touchstone and a facility to supply the induced current to the battery. (I think that the contacts for the special back were visible in that "back-off" shot from WMC.)