While maybe a good idea, (I don't think I'd use it but...) it might just be one of those ideas that is too hard to implument in such a way that the consumer would find it easy. If Apple cannot make it simple for the user, they will not do it.
I agree with pwb503... Apple is going to put in something that would be simple to the user's touch... cool idea! I know that isights can scan and read barcodes though.. and there is an Application that stores all the barcoded items, something like creating a virtual library. it would be cool for the iPhone to be able to scan barcodes in the same manner.