I see potential parallels here to the relatively recent trend of people holding phone conversations in public through hands-free wireless headsets. The act of physically holding a mobile phone usually serves a signifier that a conversation in public space is taking place non-proximately. Without the phone (or at least the act of holding the phone), it is often unclear if the caller is speaking to me, someone else in the same place, or someone on the other side of the world.
The kinds of augmented realities offered in these images are similarly enacted without devices that can act as signifiers that the user is engaging with non-proximate, or virtual, information. Will this mean that, relatively soon, we will start to see people stop in the middle of a street and wave their arms and point their fingers (see the first image) at interfaces that are invisible to the naked eye?