Very interesting. I've wondered when something like this would come out.
Funny half-hijack... Around a year or so ago, I was talking to my daughter (who was probably 12 or 13 at the time) and joked with her that we'd had something like that implanted in her when she was born. I told her it was so if she was ever kidnapped or got lost that we'd be able to find her. The story just spilled out of me; I don't know how. But SHE BELIEVED ME! All night, she kept asking me questions about it. When she was getting ready for bed, I finally came clean with her, mostly because I would have felt bad if she'd told her friends at school about it and they gave her a hard time for falling for it. I still can't believe she fell for it, though.