Bill Gates. AP Photo by Peter Dejong

Bill Gates got headlines this week with his call for corporations to adopt a new form of “creative capitalism” in a speech at the World Economic Forum in Davos, Switzerland. But he also issued a more personal call to action, made more credible by his own career shift to devote his full time to the Gates’ foundation work on global health, poverty and education.

“The passing of time requires each of us to take stock,” Gates said. “What have I accomplished so far? And what do I still want to accomplish?”

Some people – Gates, of course, foremost among them — have financial capital. But money, while necessary, won’t generate the kinds of breakthroughs needed to significantly reduce the world’s inequities, he said.

What’s needed there, he argued, is intellectual capital – innovative ways to harness market forces for the benefit of people at “the bottom of the pyramid.”

He specifically called out social entrepreneurs, “who are turning their ideas into products and services for solving problems,” and cited Fast Company’s support for “social capitalists.” (Note: Civic Ventures was a winner of Fast Company’s Social Capitalist awards in both 2007 and 2008.)

“It’s a worldwide movement and we all have the ability and responsibility to accelerate it,” Gates said.

Implicit in Gates’ argument was the need for a third kind of capital: human capital. Increasingly in schools, non-profit organizations and even businesses the factor in short supply is neither money nor ideas, but people – talented, passionate people to do what only people can do. Gates’s own career shift is recognition of this need.

Likewise, kids learning to read need one-on-one attention, and that’s what members of Experience Corps provide for 20,000 children each year. Children of incarcerated parents need adults guidance to avoid prison themselves, and that’s what the mentors of Amachi provide. Underinsured mothers with vulnerable babies need visits from health care professionals, and that’s what Nurses for Newborns provides.

At Microsoft, Gates always insisted on putting the best people on the company’s highest priorities. Now, it’s time to put the best people on society’s highest priorities, he said. ”We need another level of innovation. Not just technology innovation. We need system innovation.”

The accelerating transition of the huge baby boom generation from their primary careers into a new stage of life presents a unique opportunity for system innovation around such badly needed human capital. Creative capitalists, social and otherwise, are finding new ways to craft hybrid “encore” opportunities that combine pay with purpose – enabling aging boomers to put their huge store of experience to work on society’s toughest challenges.

Gates has set ambitious goals for his next 15 years – to have dramatic impact on at least half of the 20 diseases that account for the bulk of preventable deaths in developing countries, resulting in “a huge change in mortality rates” in those countries. His foundation is spending $3 billion a year on such projects. Over 15 years “that adds up,” he said. “People should have a very high expectation of what we can do.”

By the same token, 78 million baby boomers in America, most with a decade or more of health and productivity after they finish their primary careers – that adds up. We should have very high expectations for what we can all do in our own encore careers.