Mobiles interacting with (previously) non-networked media

On May 25, 2006 by Christy

How do you get information from a poster, a billboard, a product on a shelf or a tree to your mobile phone? Well, here are some ways:

I haven’t bothered to go through the tons of locative arts projects I’ve got catalogued but is that all? I’m interested in which are the most effective commercially, than for a one-off art project.