The idea of the Spime proposed by Bruce Sterling is outrageous and extraordinary. I love the concept of being able to track an object's existence from cradle to grave. Here a small retailer is trying to use QR codes, or meta tags to help track the life of their art pieces.
Itizen is a very neat site and offers an interesting experience. I think the challenge is that it is going to require a lot more participation to get to the critical mass it needs. Bruce would say embed an RFID chip and forget about it, but I like the requisite interaction - makes you feel more part of the story of the object.