The memorial service for Nelson Mandela is a big deal. "We're now on 91 Heads of State & Gov confirmed plus 10 former Heads of State, 86 Heads of delegations & 75 Eminent Persons," tweeted South African government spokesman Clayson Monyela on Monday. Among those leaders attending are the UN Secretary General, Ban Ki-Moon, British Prime Minister David Cameron, and French President Francois Hollande -- plus, of course, President Obama and former Presidents Carter, Clinton, and George W. Bush. Dozens of lesser leaders, plus celebrities like Bono and Oprah Winfrey, will also be there. From the United States Congress, House...