TheFeature.com has an interesting article on Intel’s new “Jabberwockey” research project. In short, it’s a bluetooth-driven system for recognizing “familiar strangers” via their phones. It runs on your phone and keeps track of other bluetooth devices that it sees, so it can recognize when those devices show up in other contexts.
Personally, I find this kind of fascinating. I don’t see the present incarnation as being particularly useful, but I love the concept. If you had a bit longer range then Bluetooth (30 feet is kind of short, 100-150 feet would be just about right, IMHO), and some reasonably standard way of mapping device IDs to people (think FOAF or something Technorati- or Google-driven, where people opt-in by posting their own IDs), and we could have a really fascinating way of building communities. There are certainly a ton of privacy issues, but those could be mostly mitigated by the opt-in nature of the device ID→identity mapping and by turning off Bluetooth discovery on your phone.