* Harry Culham update: 6 February 2008Merrill Lynch is believed to be about to unveil Harry Culham as its latest global head of foreign exchange. Culham is joining the bank from Dresdner Kleinwort, which he joined in early 2005. There he was global head of fixed income, currencies and commodities. Merrill has declined to comment but Dresdner has confirmed the departure of Culham, plus two of his colleagues. ...