One conference session will be called “Voiding Your Warranty: Hacking Glass.” But it could be controversial to encourage experimentation with a product that at once has wowed people with its possibilities and spurred uneasy imaginings of a society subject to ubiquitous, user-generated surveillance. Google clearly wants developers to help explore the limits of what Glass can do, and yet Glass is not even on the market yet, and a handful of bars and cafés have already banned the hardware.