As I understand it, something like the first 8 digits of your card number encode information about what kind of card you have. It allows the merchant to tailor how much you pay, to the type of card. It could take a couple of forms:

1. A surcharge for certain kinds of cards.

2. A discount for certain kinds of cards.

In either case, I think this is just a logical step in a progression that makes it so that a merchant can recover a portion of their credit card fees from the consumer. Good or bad? It might create an opportunity for competition among credit card processors to offer their services for the lowest possible fee.