Someone on a local 4x4 board asked a related question: Could a helicopter take off from a turntable rotating at the same RPM as the blades but in the opposite direction?

I say, discounting the tail rotor, the answer is no. The blades would be stationary in relation to the ground, therefore not moving through the air to create lift. The net effect would be the same as if you held the blades and spun up the turbine: the copter would spin under the blades.