Wi-fi and Bluetooth are integrated into a single board. Broadcom has been one of Apple's favorite suppliers recently. It's possible this is the same BCM4329 chip that Apple used in the 3rd Gen Touch.

Laser engraved on the cover:

X17B ES2.0-A4

APN 339S0107

USI 20091207

The bracket shown in the second picture is both a cable clip and a ground point for the WiFi/Bluetooth/cable assembly.