The new Palm Touchstone wireless charger works on the principle of resonant induction. When you move a magnetic field near a coil of wire, it induces a current in the wire.

Taking advantage of this principle, the Touchstone creates an electrical coupling between two coils of wire that are not physically connected. It does this with a primary coil of wire in the base unit which transmits energy to the secondary coil of wire in the phone via a magnetic field.