** ADVANCE FOR WEEKEND EDITIONS, AUG. 23-24 AND THEREAFTER -- FILE ** In this Aug. 28, 1963, black-and-white file photo Dr. Martin Luther King Jr., head of the Southern Christian Leadership Conference, addresses marchers during his "I Have a Dream" speech at the Lincoln Memorial in Washington. The 45th anniversary of the iconic leader's most memorable speech coincides with the day when another African-American leader, Barack Obama, is scheduled to makes a historic speech of his own _ accepting the Democratic Party's nomination for president of the United States Aug. 28, 2008, in Denver, Colo. (AP Photo/File)