We really just want to look at this motherboard, but we're thwarted by a (very Apple-like) fingerprint sensor cable boobie trap! Fortunately, it proves very easy to disarm.

Next is another mini board with microphone and the rangefinder that enables the XL's laser autofocus.

These smaller bits aren't always so modular; in other phones, we often find them clustered together on the main board. More modularity means cheaper and easier repairs—if a single component fails, you don't have to replace the entire motherboard or embark on a risky microsoldering adventure.

Teardown Update: This blue "mystery" component hanging out next to the main camera is likely a passive inductor, as evidenced by its two solder pads and copper wire coil.