That's the question asked in this morning's Washington Post. From the article:
Over the last month or so, Apple has clearly been on a mission to trim down the App Store to applications that are useful and family friendly. First, it removed thousands of sex-themed applications, and it's also been making moves to crack down on overly simplistic 'cookie cutter' apps. But there may be yet another segment of the App Store on the chopping block: Books. According to a recent report, books represent 27,000 of the App Store's 150,000 applications, making them the most abundant type of application on the App Store.
But given the impending release of Apple's own iBooks app alongside the iPad, and the recent App Store cleanup spree, I won't be at all surprised if they do something to change the way books are treated on the platform.
So what do you think? TBH, Apple's current behavior is too random for me to make a prediction. They banned sex themed apps and yet left Playboy and Sport Illustrated. I doubt they even know what they'll do next.