The Credit Card Accountability and Disclosure Act (CARD) finally goes into effect goes into effect todayThe law was changed in response to years of consumer complaints about abusive behavior by credit card companies. Here are some of the  principal changes:

Payment crediting
Under the new law, if you pay more than the minimum monthly payment, the excess will be applied to balances with the higher interest rate. Currently, the credit card companies can apply it any way they choose, and usually choose to apply it to the balance with the lowest interest. The purpose of this particular change is to allow consumers to pay off their higher balances more quickly, saving on interest charges.

Paying interest
You will have a minimum of 21 days following the close of each billing cycle to pay off the balance to avoid accruing periodic interest charges. Cash advances, however, may still carry an interest charge, even if you pay it back within 21 days. The 21 day window was added because many consumers complained there was so little time between the time they received their monthly statement and when the payment was due

Read more: http://www.consumeraffairs.com/news04/2010/02/credit_card_changes.html#ixzz0gMJ1Bja2