Gregg Liebman has joined Turner Broadcasting System as vice president of CNN ad sales research. In his new role, Liebman is charged with leading staff research analyses and strategy support for the CNN News Group, which includes CNN/U.S., CNN Headline News, CNNfn, CNN.com and other CNN-branded news networks and services. Based at the CNN ad sales New York office, he reports to Jack Wakshlag, chief research officer for TBS, and works closely with Greg D'Alba, chief operating officer of CNN ad sales. Most recently senior vice president and research director at Zenith Media, Liebman led a team providing research and analysis for clients including Georgia-Pacific, General Mills and Miramax. Earlier in his career, he served as media research director at Double Click; worked in the media research departments of J. Walter Thompson and Foote Cone & Belding; and was manager of ad sales research for MTV Networks' Nickelodeon, Nick at Nite and TV Land.