Just found an article about this exact issue....
Credit card holders livid about 'rate-jacking' - CNN.com
As I mentioned elsewhere, I'm getting the rate on my primary CC moved up from 7.9% to 9.9%, which will take effect in Feb. I'm personally just fine with that, because I don't ever carry a balance, so the rate doesn't mean much to me. However for the millions that do carry large balances on CC's, this kind of thing is going to be pretty hard-hitting. I see the best way to mitigate this problem is to "grandfather" people's current balances at their current rates, but say that all charges after a given date will be assigned the higher interest rate.