Natalie Portman wore this Jason Wu Oleg printed silk-chiffon dress (available from Net-A-Porter, $3995) while at the “Black Swan†premiere September 13th, 2010, in Toronto (Source).
Black and white silk-chiffon strapless dress with a floral print. Jason Wu dress has a bandeau neckline, ruching at boned bodice, a fitted waist, tiered layers with raw distressed edges through skirt, a concealed zip and hook fastening at side, and is fully lined.