Kate Middleton Photos - Prince William, Duke of Cambridge and Catherine, Duchess of Cambridge prepare to leave Westminster Abbey following their marriage ceremony, on April 29, 2011 in London, England.  The marriage of Prince William, the second in line to the British throne, to Catherine Middleton is being held in London today. The marriage of the second in line to the British throne is to be led by the Archbishop of Canterbury and will be attended by 1900 guests, including foreign Royal…