Hyper-active Swiss curator tops artworld power listHe is one of the most colourful figures in the artworld today, just as likely to be giving a talk in Beijing, or publishing a book in Germany as doing his day job as co-director of exhibitions at the Serpentine Gallery in London. Now Hans Ulrich Obrist, not so much a curator as a human whirlwind, has been anointed as the most powerful figure in the international artworld, taking the top spot in Ar
