I began by trying to design an interface which started like Google Maps, but similarly to the Nolli map of Rome, it 'zoomed in' to show all public spaces, even interior ones. Then, on a per-person basis, it could show even private spaces, down to the scale of a single office, desk, or even computer desktop. The interface would have an awareness of what kind of device it was being viewed on - a public kiosk, or a private smartphone, and would show information accordingly.

I then thought of using a public bulletin board more effectively by time multiplexing it so that messages could be targeted at specific groups of people, or related in real time to events. Messages might be conditional on certain data; an author might specify that it should only show if a group of people is there, or only if a single person is there.

If unique IDs existed per person, messages could be triggered to appear only for a specific person at a specific time or place; "To: John in the Atrium between 3pm and 6pm". Private messages could be marked to display only if the recipient is alone – they might see that they *have* a message, but unless they 'opened' it it wouldn't display in public. Messages could be triggered by two or more people, regardless of location or time... "To Bob and Mary before Feb 14th" would show when both are together only.

"Matt" could leave a message for his friend at the front door that says "John, come this way!" from his computer or mobile device. Matt could then leave a trail to guide John to where he's working - and could have the trail update with wherever he goes. That way if Matt goes down to the optics lab, the trail still leads to him, either by reconfiguring or simply by breadcrumbing his convoluted route. Matt could leave additional notes along the path, or could even suggest detours or alternate destinations: "It'll be a while; maybe you should visit Doug >>"

Sketches on Flickr