I agree that wireless power transmission, in the utility sense, is not practical. But with the lower power consumption and desire to eliminate connectors on portable devices, wireless battery charging will come into its own. The charging frequency will be in the 100s of kHz to more efficiently transfer power over a small air gap/core. I was reading up on a clever Linear Technology design that limits the charging current by detuning the receiver tank circuit. Those interested can go to DigiKey and download the datasheet for the LTC4120. The switching frequencies, close to 1MHz, refer to the battery charger converter. The actual power transfer tank is running at around 130kHz.
Joe
