Thanks to Samer Muhi for sending in a video of his latest Quadrotors Wireless Power Transfer project. He is able to power his quadcopter with up to 20watts of energy using resonant inductive coupling. You can see the main coil sitting on the table which is operating at a resonant frequency is 800kHz. On the quadcopter arms you will see the second coil and some circuitry in the board in the center.