The art world has officially joined the rest of the world in a maniacal obsession with celebrity culture. Sure, Warhol did it long ago with his 1960s “screen tests” of Warren Beatty and Dylan, and by hosting the likes of Mick Jagger, Jackie O, her son John John and sister Lee Radziwill in Montauk in the ’70s, then hanging with Halston and Liza Minelli throughout the ’80s. But these days, celebrities and art are hooking up in a whole new way.