Thanks Vlad for pointing me on Drop Spots:
A dropspot is a kind of alternative mailbox. It’s a hiding place in a public space, where people can leave things for exchange. Anything. It’s a weird and wonderful way to add personal character to the streets that we live in. Stash something fun and see what you get back.
To find a Drop Spot in your neighborhood, visit the Drop Spots map. Select a Drop Spot map marker near you, make note of its location and visual description and head out the door to find it! Once you locate the spot and discover your mystery gift, make sure to leave one in its place to keep the exchange going.
Why do I blog this? yet another interesting potlatch-like approach of sharing in today's environment. Similar to bookcrossing but there is here the notion of exchange. I also appreciate the idea of "alternative mailbox", which is somehow a portion of territory where people leave traces. I have to admit that I am more interested by this sort of innovation than yet-another-place-based-annotation-systems (virtual post-its) that seem to pops up everywhere. This is exactly what Georges Amar explained at the CINUM2006 presentation last week: he described how pedibus (a non technological innovation but a practice: a walking school bus) is one of the most interesting innovation he ran across lately.