Can the poor have great design? Yes, according to architect Alejandro Aravena. This week he won the biggest prize in architecture, The Pritzker Prize. Aravena, 48, is from Chile. The Pritzker jury cited his innovative work in social housing and in rebuilding cities after natural disasters. In a recent TED talk, he said he tries to involve regular people in the design process. We get a primer on his work.