From The Apple Wiki
New Sightglass icon
Old Sightglass icon

Sightglass is an internal SwitchBoard application for launching NonUI bundles. The icon of the app was the logo of a coffee shop in San Francisco called Sightglass Coffee, however it has since been changed to a 3x3 grid of colored dots on a brown background.

On watchOS, SwitchBoard is not present and apps are launched from Sightglass. It retains the ability to run scripts, and can also be used to power off or restart the device, as well as setting whether the display should be kept on or not.

You can load additional scripts into Sightglass by placing them in /private/var/logs/Sightglass/Scripts. Outputs of scripts are displayed while they are running.

Contents of the App (iPhone):

ChicagoFLF.ttf		           Sightglass
_CodeSignature.                    _internal_reset_pedometer.png
Info.plist			   Sightglass-Apps.plist
_internal_apps.png.                _internal_scripts.png
PkgInfo.                           Sightglass-BootTasks.plist					
_internal_get_pedometer.png        _internal_sightglass.png
ResourceRules.plist		   Sightglass-Help.plist

External Links

Article about iPhone 6 prototype on MacRumors

Main screen and app list on watchOS

Sightglass Coffee