CAIRO, Egypt - In a surprise and dramatic reversal, President Hosni Mubarak (news - web sites) took a first significant step Saturday toward democratic reform in the world's most populous Arab country, ordering the constitution changed to allow presidential challengers on the ballot this fall. An open election has long been a demand of the opposition but was repeatedly rejected by the ruling party, with Mubarak only last month dismissing calls for reform as "futile." The sudden shift was the first sign from the key U.S. ally that it was ready to participate in the democratic evolution in the Middle...