New York--AOL Time Warner Inc. on Monday announced that Walter Isaacson, the former editorial director of Time Inc., has been named chairman-CEO of the CNN News group. Isaacson, a 23-year veteran of Time, replaces Tom Johnson, who stepped down in June. In his new position, Isaacson will be responsible for CNN, CNN Headline News, CNN International, business channel CNNfn, CNN SI and CNN en Espanol. Most of the CNN outlets, particularly CNN and CNNfn, have become strong b-to-b marketing vehicles in recent years. Isaacson will also oversee CNN's cable, radio and satellite television networks as well as its 12 Web sites.