At the end of Google's keynote yesterday, Sundar Pichai announced that all I/O attendees would receive either an LG or Samsung Android Wear device, along with Moto 360 when it becomes available later this summer. But he also offered up an unexpected gift... the slide read #cardboard (yes, with the hashtag) and Pichai held up a small brown square, barely large enough to accommodate a thin book for shipping purposes -- but Google had something else in mind. Once assembled, #cardboard serves as a head-mounted 3D viewer, using your own smartphone and a pair of integrated lenses to create the effect.
