Every Tuesday and Wednesday night, almost 30 million people grab a snack, get their dialing fingers ready and clear their schedules for the most watched show on television—American Idol.

Ryan, Simon, Paula and Randy are still working with this year's talented new crop of contestants, but producers have already shaken up a few things this season. There's feisty new judge Kara DioGuardi and a new rule that could change the entire competition...