Here’s how leadership can spread: In 2006, Fortune and the U.S. State Department launched the Global Women Leaders Mentoring Partnership. Every year since then, we’ve selected two dozen or more of the best and brightest young women leaders in developing countries and invited them to the U.S. to shadow women who attend the annual Fortune Most Powerful Women Summit. Mentor/CEOs like Andrea Jung of Avon , Ellen Kullman of DuPont , Ann Moore of Time Inc. , and Ursula Burns and Anne Mulcahy (now chairman) of Xerox –plus top women execs at companies like Wal-Mart and Exxon-Mobil–have hosted these international women. Ideally, the mentees return home and apply what they learned to improve their own community.

To reward the mentees who most effectively pay it forward, so to speak, Fortune has partnered with Goldman Sachs –which has created its own program, 10,000 Women, to educate and mentor rising-star businesswomen in emerging markets. Last Thursday, a team of judges convened to select a winner of the Goldman Sachs-Fortune Global Women Leaders Mentoring Award.

It was really difficult to choose among the 26 nominees.

There was Maria Pacheco, a 2006 mentee who, after completing her month-long stint in the Fortune-U.S. State Department program, went home to Guatemala and built a network that today connects 1,000 rural craftswomen to markets. With help from United Nations Foundation COO Kathy Bushkin Calvin, who was her mentor, and an ever-expanding web of contacts in the U.S. and Guatemalan governments, Maria recently launched a U.S. company, Wakami World, to distribute the craftswomen’s products.

There was Maria Gabriella Hoch, the head of a Buenos Aires communications consulting firm and a 2007 mentee at NBC Universal. Maria connected with Clarissa Eseiza and Lorena Piazze–fellow Argentinians who had participated in last year’s program. Together, they set up a multi-faceted mentoring and leadership training program for women in their country.

And there was Lucy Kanu, a 2008 mentee at Exxon-Mobil (XOM) who returned to Nigeria and drew more than 500 women to her “Women Mentoring Women Walk.” Lucy modeled the event on a Mentors Walk that Gerry Laybourne, the media entrepreneur, started doing in New York’s Central Park when she was CEO of Oxygen Media. Laybourne invites the Fortune-U.S. State Department mentees to her home each year when they’re all in New York City for the close of their month-long visit. The stories she shares are infectious. Inspired by Laybourne–and by Lucy Kanu in Nigeria–alums of the mentoring program have staged “Women Mentoring Women Walks” in Kenya, Ghana, Serbia, Argentina and Peru.

Laybourne was one of the judges who helped select the winner of the $50,000 Goldman Sachs-Fortune award last week. She told me that she wept as she read the 115-pages of nominations and mentors’ endorsements.

Choosing a winner was difficult, as I said. But the judges settled on two women who have extraordinary stories and compelling plans to use the money–$25,000 each–to improve their communities.

Brigitte Dzogbenuku is one of the winners. Last year, she was the mentee of WNBA President Donna Orender. Brigitte, now 40, went back to her country, Ghana, and created not only a Mentors Walk but also a program called Hoop Sistas, which is a basketball club to teach girls teamwork and self-esteem. Brigitte, who is take-charge and charismatic, plans to use the award money to expand Hoop Sistas beyond Accra to four other cities in Ghana.

The other winner is Penelope Machipi, an alum of Goldman Sachs’ 10,000 Women program in Zambia. Penelope is a shining example of what mentoring can do. A decade ago, when she was 14, she had lost her parents and her family property. She quit school and turned to prostitution to support herself and her brother. With the help of Camfed, a U.S.-based non-profit than fights poverty and HIV/AIDS in rural Africa by educating girls, Penelope got back into school and started a business selling maize. She applied to Goldman’s 10,000 Women and graduated this year.

Now trained in IT, Penelope is managing a computer resource center in Samfya, a remote spot in northern Zambia. The center has nine “green” terminals, an Internet connection, a printer and a photocopier. It’s managed by a team of women, and about 200 girls and women use the center each month.

That’s Penelope’s day job. Her real passion is film-making. Partnering with 22 other women in Samfya, she made a film called Nasange Inshila, meaning “I Have Found My Way,” and the group–calling themselves Samfya Women Filmmakers–has screened it in communities across rural Zambia. They’re planning to make a documentary about gender-based violence.

Penelope and Brigitte will come to the U.S. next month to attend the Fortune Most Powerful Women Summit. Goldman Sachs CEO Lloyd Blankfein will be on hand opening night to present the Goldman Sachs-Fortune Global Women Leaders Mentoring Award to each of these two remarkable women. Dina Powell, a former assistant Secretary of State who is now a Goldman managing director overseeing 10,000 Women, will be there too. She and I, sitting in her State Department office one day in the summer of 2005, dreamed up this Fortune-U.S. State Department Mentoring program. We hardly imagined the global power of one small idea.