Just new and exciting ways for banks to make up the revenue lost for the new overdraft laws.
Not really, this is a way to prevent overdrafts. When you run you're card they put a hold on an amount of money that you could reasonably use to fill up your tank. If you have less than the amount they use for the hold I assume that the bank will refuse the transaction. It keeps people from low amounts left in the account from running their debit card and then filling up with more gas than they can pay for with the money left in the account.
As far as I know when the merchant pings the debit/credit company about a transaction they don't get a message back saying how much money you have left in your account, they just get a yes/no answer if the charge is accepted. For most purchases you know the full cost ahead of time and the bank can compare that to how much you have in your account so that's no problem but for gas there's no way for them to know that until you're done.
I pay my cc bill in full every month. Card companies hate me, as they NEVER get any interest or late fees. And my cards come with No Annual Fee .. so they lose all around with me.
Don't kid yourself, they still make money off your transactions. The merchant has to give them a percent of your transaction. While you don't see it tacked on top of what you pay the costs to the merchants do raise prices for everyone overall because it's part of the cost for them to do business.