As the New York Times noted, ING has given full disclosure in the fine print that they "may change the Interest Rate for your account at any time."
Of course, those who have a lot of money sitting in the bank will be feeling the effects of the drop more. For example, those who have $10,000 sitting in the bank will be earning $90 a year instead of $100, which means a loss of $10. Those who have $100,000 in the bank will lose out on $100. Although it's a 10 percent drop, the current interest rate is still considered high for a savings account.
Would this drop make you switch banks?