Jessica Alba traded her stunning Gucci red-carpet gown for a glittering strapless mini from the label. "Everyone decided that it was an awesome idea to step on my train," she joked of her last-minute switch-up. "I was like, 'Oh wait, I live up the street. I'm going to change out of that one.'" Super-stylist Rachel Zoe stood by in a flowing dress from her spring collection.