The top prize in Mr. Gates' "Reinvent the Toilet Challenge," says Reuters, went to California Institute of Technology for a "self-contained, sun-powered system" that "breaks down feces and urine into hydrogen gas, which can be stored in hydrogen fuel cells to provide a back-up energy source for night operation or use in low-sunlight conditions." Better still, water recovered from the process can be pumped again to provide water to flush the toilet. That, my friends, is a lean startup.