When one refers to "unibody" they are referring to the unibody frame from the MacBook Pro. Frame.
The iPhone doesn't have a frame; the circuitry is encapsulated within a shell. Therefore, it is non-sensical to talk about unibody with respect to the iPhone.
Actually from the take apart pictures, it does quite look like the metal chassis part of the phone is made using same manufacturing technique as unibody chassis for macbooks. so it may well be.
When one refers to "unibody" they are referring to the unibody frame from the MacBook Pro. Frame.
The iPhone doesn't have a frame; the circuitry is encapsulated within a shell. Therefore, it is non-sensical to talk about unibody with respect to the iPhone.
That's my point. All previous iPhones have been assembled with multiple layers of metal encased in plastic.
The new iPhone seems to be a single piece of metal that the screen and digitizer would be attached to and then the glass/plastic/ceramic be attached to the back.
The unibody MacBooks are made in a similar fashion with the entire "frame" (chassis) made of aluminum and the internals placed in afterwards. It is then all covered with the aluminum plate with the eight screws on the bottom.
A unibody to me would mean that it would be like the MacBook pros, where the electronics would slide into the frame. That video clearly showed 2 pieces. The aluminum frame was open. There was the black piece to contain the electronics.