It's the combination: big idea with a good entrepreneur: there's nothing more powerful.
We started Ashoka here in India with a simple idea: that you needed social entrepreneurs to deal with problems that don't fit the business paradigm.
Entrepreneurs almost always have to step out of existing institutions that embody old ways of doing things to build their vision.
Organizations must shift away from repetitive-function hierarchies with rules and enforcement and walls. Instead, we must migrate rapidly to becoming a global 'team of teams' that comes together in whatever combination necessary to add the greatest value to the changes underway.