False Registration Robots

This has become a major problem.
Robots signing up on wordpress sites I think there should be totally new approach to wordpress registration system.

1) If a registration is not confirmed within 30 minutes the registration is removed from the database the email address is flagged and can only be restored by the admin. Maybe if the profile requires a secondary activation link to keep the activation live.

2) A second activation link could also be considered a simple question and answer quiz to protect the registration form.