As an addition to an earlier post Social Impact and Profit, I want to point to a recent paper by Stanford's James Phills who takes a closer look at the role of the social entrepreneur in the marketplace.
In Social Entrepreneurs: Correcting Market Failures, Phills writes:
At times, when a market failure affected a population's access to food, shelter, clothing, medical care, or other basic necessities, charitable organizations also got involved. However, private businesses were rarely called upon (or expected) to respond to breakdowns in efficient market operations by modifying their behaviors in a free-market system. However, a new class of actors has recently gained recognition. These individuals often found and manage organizations drawing on innovative ideas, using entrepreneurial skills, and leveraging market principles, but with one important difference from traditional entrepreneurs they prioritize social impact over the creation of wealth.