That is not exactly the case - atleast with many of the credit cards I've seen in the past few years that gave cash back. In almost all of those cases (specifically the non-529 ones), you had to initiate getting the cash back by specifically requesting it. We had the Citibank/UPromise card which automatically did the transfer, but then switched to MBNA/Fidelity. With a number of them now (some Citibank cards specifically - actually identified in the WSJ in the last day or two), they are even starting to take away accumulated awards if you don't request them or you don't have enough to get cash back in 6 months or a year.
With the cards giving 5% back on gas and only 1% on other stuff, they realized that people were only using it for gas - so they are going to reduce the rebate amount.
On all the Citibank cards, they have a yearly cap of $300 cash/rebate back.
It is not simply a matter of getting the most bang for your buck, but how much work do you have to do to get the money? In the end, as Mark says - I don't want to do any work, I just want to go about my daily business, use the one card where/when I want, accumulate the rebate and have them automatically transfer it at regular intervals. With the MBNA/Fidelity Mastercard at 2% on all purchases and a $1500 annual cap, it does what I need it to do. I don't have to carry more than one credit card and think "ok, I'm at the grocery store, which card am I going to use here"?
Lastly, I sincerely hope that everyone who is contributing to this thread and is carrying one of these cash/rebate credit cards pays off their balance at the end of every month. If you are carrying a balance and paying 10%, 15% or more because you carry a balance, I really couldn't care if you were getting 1%, 2% or 5% back - you'd be better off paying the balance off because you'd save much more in interest and fees than you'd ever accumulate in rebates.
[This message has been edited by rsinj (edited November 16, 2005).]