The UI Overview Slashgear wrote up via a leaker(http://www.slashgear.com/google-glass-in-focus-ui-apps-more-22270783/ http://www.slashgear.com/google-glass-in-f

The UI Overview Slashgear wrote up via a leaker(http://www.slashgear.com/google-glass-in-focus-ui-apps-more-22270783/ http://www.slashgear.com/google-glass-in-focus-ui-apps-more-...) says that the swipe down gesture on the touchpad takes you up a level within the UI, and swiping down at the topmost level turns off the screen completely.