From Howard Kurtz' column in today's Washington Post:

CNN is restricting appearances by two of its high-profile commentators, James Carville and Paul Begala, until the Democratic presidential contest is resolved. Because both are personal supporters of Hillary Clinton, says CNN political director Sam Feist, they have not appeared since November, except as Clinton advocates balanced by spokesmen for one or more of her rivals. The policy, first reported by Talkingpointsmemo.com, followed complaints from Barack Obama's camp. Feist says GOP analyst Rich Galen was similarly restricted after joining Fred Thompson's campaign.