Apple may bring wireless charging to the iPhone in a future iteration, but it likely won't use the same induction charging technology popularized by Palm's Touchstone charger. Instead, the company will likely implement more exotic near field magnetic resonance charging currently being championed by wireless power startup WiTricity.
Induction charging works by inducing a current in a coil of wire from one device to another. A charger device (Palm's Touchstone charger, for instance, or a mobile device "charging mat") contains a large coil of wire inside. When a current passes through the coil, it creates a small magnetic field around the coil. When a second coil—embedded in a mobile device like a smartphone—is brought into close proximity of the first coil's magnetic field, it induces a current to pass through the second coil.