[thinkcomp]

The additional hardware (plus integration cost) is something that reatilers don't want to spend on.

In contrast, barcode scanners are already there and they typically emulate keyboards, so no special integation is required.

I'm not convinced that paying with your name scales for most retailers. The retailers I've talked to aren't convinced, either.

[gojomo]

Barcode scanning is another good option to speed the initial account-identification.

I suspect in coming years, multiple systems will all work together to train users to bring up barcodes on their handhelds for specific purposes (as with boarding passes or "Jonathan's Card").