An entirely-new side of the logic board:

Apple A5X processor

Apple 343S0561 - This IC looks like an updated version of the 343S052 that we found in the iPad 2, and is used for power management.

The NAND, part number THGVX1G7D2GLA08 is a 16 GB 24 nm MLC Flash from Toshiba

Qualcomm MDM9600 - 3G and 4G wireless modem

Skyworks 77469

Avago A7792

A big and hearty thanks to Chipworks for helping us ID these chips!