This month’s Vanity Fair “green” cover has a pedigree. “A spokeswoman for the magazine acknowledged Wednesday that the cover photo of Robert F. Kennedy Jr., George Clooney, Julia Roberts and Al Gore, shot by Annie Leibovitz, was “inspired” by “Ballet Society,” a 1948 portrait by Irving Penn of George Balanchine and three collaborators. Although there’s no mention anywhere in the magazine of the connection, the composition of the two photos is virtually identical, down to the leafy garland on Roberts’ head.”