Sneakily hidden on the backside of the logic board, we find a few more chips:

Intel DSL3510L Cactus Ridge Thunderbolt controller

Analog Devices SSM3302 audio amplifier

Vimicro VC0359 webcam processor

Intersil ISL6364 multi-phase pulse width modulation (PWM) controller

Cirrus Logic 4206BCNZ audio controller, the same chip as found in last year's 21.5"