The blog site Marginal Revolution has a post on the entrepreneurial generation and a link to an article he wrote for the New York Times.
American youths are so successful at entrepreneurship in part because so many older and wealthier people are willing to help them. The broader American success at philanthropy, then, lays the groundwork for American entrepreneurship. By global standards, Americans may have looser networks of friends and family, but Americans are more willing to help relative strangers, and this often helps business.
(Thanks to Ben Cunningham for passing this along).