In an article entitled "Businesses try to make money and save the world" published in the New York Times, Stephanie Strom makes the point that some organizations are trying to mix social purpose and financial promise, and gives several examples of traditional companies going the responsible investment route, and several charities being more aggressive in their investments - and calls this the fourth sector. She asks the question - are these still for-profit businesses and nonprofit fund-raising machines? I think she is on to something - we are seeing more and more of these hybrid organizations. You can't simply classify institution under government, business and non-profit anymore - there seems to be convergence with companies trying to be socially responsible and acting for the common good (companies are at different stages along this path), and non-profit institutions concentrating on efficiency and good use of funds. Pretty soon we will be seeing all kinds of rankings on both sides to measure how good they are, and how much progress they are making. So I would argue that in very short order this will no longer be the fourth sector, but the mainstream.