EDM doesn't nearly give the same yield and precision compared to laser.
EDM skimming probably get the job done nice and accurately, but it will cost just too much time.
Obviously the internals of the iMac / Macbook unibody frame are being done by traditional mill-cut CNC. It does take a while before a frame exits the machine, but Apple just has an awful lot of them in the factory. No rocket science here.
The Apple logos (front and back of the iMac, screen lid of the Macbooks) are probably done by laser cutting. To get higher yield, they might use high pressure waterjets (possibly assisted with garnet and/or alox) for the middle, and laser for the outer edges.
Not your question but nonetheless interesting, the breathing light on MBP's, the LED non-hole next to the Macbook's iSight camera/external touchpad/keyboard are done by high precision laser technology (0.001" and below) with machinery sourced from an external company which owns the technology behind it.