According to the latest Publisher’s Lunch:

Viacom to Split; Simon & Schuster Goes to CBS–for Now
The Viacom board announced their approval of splitting the company in two yesterday, with the “growth” assets retaining the Viacom name and the “mature” assets–including CBS, Paramount TV and King World, Infinity Broadcasting, Showtime, the outdoor advertising group and, yes, Simon & Schuster–going under the moniker of CBS Corp., run by Les Moonves. (Please note, if you rely on the NYT for your news, they get the Simon & Schuster story wrong today.) Viacom will announce more specific details over “the next several weeks.”

Speaking from personal experience, chairman Sumner Redstone quipped, “Sometimes divorce is better than marriage. In this case, one and one will make three.” He also reaffirmed his interest in selling Simon & Schuster entirely: “We’ve had a lot of unsolicited interest in the theme parks, which is not growing at a pace we would like for the new companies,” Redstone said. “Neither is Simon & Schuster, which I would be sad to lose, but it doesn’t grow the way I want these companies to grow. So at the right price we would consider looking at (selling) Simon & Schuster.”
Redstone in Reuters