i-mature and RSA announced a partnership that uses bone scanning technology to determine a person’s age:

The partnership will work towards a unique solution that would genuinely improve the safety of the Internet for children, by enabling both adult and children’s sites to restrict their content more reliably to their appropriate audience.

i-Mature has developed an innovative technology that can determine, through a simple biometric bone-scanning test, whether a user is a child or an adult — and thereby control access to Internet sites and content. AGR technology could help prevent children from accessing adult Internet sites and prevents adults from accessing children’s sites and chat rooms.

Dave Farber has posted an extensive discussion of this topic here, here, here, here, here and here.