The Platform Controller Hub is all the I/O - USB, SATA, additional PCIe, SPI for Flash, LPC for embedded controller, etc.
On the back-side there is an NXP DisplayPort switch and a Lattice programmable chip for switching LVDS going to the LCD display. These are the same chips use to switch between the 9400M and the 9600GT in the previous unibody MacBook Pros. So I wonder if Apple could add automatic GPU switching to them as a sotware update?
It looks like the Realtek ALC885 audio chip has been replaced with something else. I can't tell if the Cirrus labled chip or the chip with first line GL137 is the new audio chip. I figure one is the audio chip & the other is the SD card controller. I have tried to search the web for what these parts could be but I haven't had any luck.