Interesting choice...I thought maybe he had gone to MIT but apparently he dropped out from Harvard. I wonder what led to him being chosen (and I say that as a fan of his)?
Perhaps a combination of factors? He was born in Cambridge, MA. MIT celebrated 100 years in the city. And Good Will Hunting.
Probably Good Will Hunting.
More likely connections between the water.org people and the MIT Corporation board. The MIT D-Lab has goals and approaches closely related to water.org's.