iMac with Retina 5K display
I am really curious about the technology behind the 5k iMac. I am not sure if there is any off the shelf GPU out there that can drive that display using retina type rendering.
It's interesting they did a custom controller for the display timing (Timing Controller (TCON)) . They must have had to do deep customizations to use the AMD R9 M290X (comparable to the Radeon HD 7870) to drive it.
If this is not innovative I am not sure what is, in terms of an engineering standpoint.