Although the rules don't go into effect asap (look for a July 2010 launch date), they will allow credit card companies to raise interest rates only on new credit cards and future purchases or advances, rather than on current balances. So that Michael Kors tote you charged last month? It's in the bag.
The changes mark the most sweeping clampdown on the credit card industry in decades and are aimed at protecting consumers from arbitrary hikes in interest rates or inadequate time provided to pay the bills.
For more on all things credit cards, read "My Credit Card, My Self."