Beginning tonight at 8 ET on Fox, the ninth season of "American Idol" begins with a notable absence: from now on, no more Paula Abdul. What Fox announced yesterday, though, was a coming change of much more significant proportions: Simon Cowell will be leaving after this season, and launching his own talent-search series, an American variant of his British hit, "The X Factor", in fall 2011. And just like the latest Leno shuffle, this move has major TV implications...