The CPU is probably a MCIMX233CJM4B or maybe a MCIMX233DJM4B (the latter is only spec'd for temperatures down to -10 C, which wouldn't be suitable for a watch) and come in BGA169 packages.
Since the CPU only has 32 KB SRAM, external RAM is needed (supported types are mDDR and DDR1) and can most likely be seen next to the 4 GB flash and the CPU itself in the presentation video on their site (3:42).
The CPU has many things built-in such as a resistive touch screen controller, 1.5W speaker amplifier. It also has a host of interfaces; SAIF (Serial Audio Interface) which according to the data sheet could provide hardware accelerated Bluetooth audio, I2C, 2x SSPs, 2x UARTs, JTAG and USB with host mode.
The circuits are split into 2 separate boards, maybe with the Bluetooth chip on the board opposite to the one with the CPU on it.
The SSPs are basically highly configurable serial interfaces and also natively support the SDIO interface, which in turn might enable us to hack in some cheap SDIO WiFi card (found out there's a TI 1271 chip which someone used with Android and a Beagle Board link). Reaching this connector might not be possible from either the hardware nor the software side, but I'm an optimist .
Data sheet for the CPU is available here, I'd recommend page 33 and 1411 to get your inspiration going.
CPU is narrowed down to 2 options
WiFi might be possible with extensive hacking