The issue of a national biometric authentication program is brought up in The Industry Standard. The authors suggest that such a scheme would be useful for "maintaining and defending our control of our own identity and personal data".

Which brings to mind an interesting point: our fingerprint, iris scan, or what have you becomes yet another piece of personal data that we have to worry about maintaining control of. Presumably this piece of data would be managed by a government agency or contractor, and one would question how well this data would be protected.