If we could have any Valentine, it would probably be Olivier Theyskens . The boy's got charm, talent, and sex appeal in spades. Last night both of his traits were on display as Barneys New York hosted a fifth-floor fête for the designer's new Assouline tome, Olivier Theyskens, The Other Side of the Picture, a heavy career retrospective. The dude who revived both Rochas and Nina Ricci let us in on his hair secrets...or secret, as it were. "I don't touch it--ever," he said. Guests like Michael Macko and Sally Singer are all breathlessly wondering what his next move will be, while Anna Wintour, who arrived in a flurry of flashbulbs, probably already knows.