After a quick look, I like the idea - but I have a couple of reservations.
1. I can only see this working with any effectiveness if the item is put up for sale on an broad audience sales channel, such as eBay, OZtion or Trading Post (online or print).
2. After looking at some of the listings, people are going to have to provide photos. Also, that those photos are decent and useful - showing identifying features. All to often, people don't have any when something gets nicked and then it's a bit late...!
3. I haven't looked too hard, but is there any indication as to how the site's effectiveness is to be communicated? It would need to show success to draw in more listings.
4. What controls are there for preventing malicious or false entries?
I'm not against the idea at all, just consider me playing
devil's advocate .