I had breakfast today with some extraordinary college students — all women, all majoring in the sciences. That alone makes them extraordinary. After all, women constitute 46% of the U.S. workforce today. But women hold only 26% of the jobs in engineering science and technology. Fewer than 10% of American engineers are women.

The young women whom I met this morning are trying to change that, and we’re cheering them on. They make up the first class of participants in the National Math + Science Young Leaders Program, a new partnership between Fortune, ExxonMobil , and the National Math + Science Initiative.

If you read Postcards regularly, you know about the Fortune-U.S. State Department Global Women Leaders Mentoring Partnership, which is another offshoot of the Fortune Most Powerful Women Summit. That global mentoring program, launched in 2006, is a remarkable success: 32 rising stars from 23 developing countries came to the U.S. for a month this spring and were mentored by America’s top women execs. This new mentoring venture is aimed at filling a glaring gap here at home.

We already have an impressive lineup of mentors. Three of ExxonMobil’s senior women — VP of global marketing Margaret Mattix, VP of Engineering Sara Ortwein, and VP of Geoscience Pam Darwin — are mentoring college students in Texas, close to their offices. The other mentors are venture capitalist Ann Winblad of Hummer Winblad, Kendle International CEO Candace Kendle, and Kathy Button Bell, chief marketing officer at Emerson , the $25 billion manufacturing and technology company.

And there’s one “mentor-at-large” who coaches via National Math + Science Young Leaders webinars: Sally Ride. Yes, the astronaut. Ride, a regular at the Most Powerful Women Summit, now has a company, Sally Ride Science, and has dedicated her post-orbit life to encouraging girls to go into science and math.

The young women who bravely venture in that direction — and help to ease a tech talent drought that’s only worsening — need role models more than ever. Mentee Stephanie Ren, who is an electrical engineering major and computer science minor at University of California Berkeley, noted this morning that guys outnumber girls by close to 10 to 1 in her computer science classes. Ren also said that after spending a day in Silicon Valley with Winblad recently — and meeting some of the veteran VC’s high-powered pals — she came to believe that she has a shot at living her dream: to work at Google someday.

Incidentally, Ren said that after Google, she envisions becoming an elementary school teacher. (I tell everyone “Don’t plan your career” — and said the same to these young women at breakfast — but I applaud Ren for aiming to “pay it forward” to the next generation of techies.)

At the least, this new National Math + Science Young Leaders Program will give smart young women a little more confidence to be pioneers. Another mentee, Therica Grosshans, who’s a geology major at the University of Houston, said this morning that visiting ExxonMobil and getting to know her mentor, Pam Darwin, changed her outlook on her own career. Says Grosshans, “She made me feel that I can get that far.”