Vehicle emissions guru Michael Walsh was at Dulles International Airport last Tuesday catching a flight to Frankfurt when he got the news. Orchestra conductor Marin Alsop had just returned to her Denver home Wednesday from Australia and was doing laundry. Documentary filmmaker Edet Belzberg was walking down Seventh Avenue in New York when her cell phone rang.

A serious voice on the phone asked Belzberg if she was alone. She said she was. The voice asked if she had somewhere to sit down. "No, but please tell me what's going on," she demanded, worried something bad had happened.

She walked into a mattress store and sat on a bed. And there she found out nothing terrible had happened. Quite the contrary.

In what has become an annual rite for the world of out-of-the-box thinking -- and for the rest of us who are simply intrigued by genius or huge cash windfalls -- the John D. and Catherine T. MacArthur Foundation at 12:01 a.m. today announced the 25 new honorees of the MacArthur Fellows Program. Over the past week, the foundation blindsided each of the newest fellows with a similar telephone call. They had been selected to receive $500,000, paid over the next five years. They can spend the money however they choose -- no strings. But each could tell only one person until the MacArthur folks broke the secret today.

"I'm on a cloud actually," says Walsh, 62, an independent emissions expert who travels from his Arlington home all over the world, telling governments and industries how to reduce the impact of internal combustion engines on air quality. "I have always believed that the areas in which I'm working are very, very important," he says, adding that 800,000 people die prematurely each year from air pollution. "But this wasn't on my radar. I'm not a genius. I'm a normal ordinary guy, that's all I am."

The fellowships are like winning the lottery for creative brainiacs. The street name is "genius grant," but the foundation avoids the g-word, insisting that the fellows bring more to the table than high IQs.

MacArthur Foundation President Jonathan F. Fanton says the rigorous, formal vetting process involves hundreds of nominations each year and thousands of evaluations. The field is whittled to a diverse few who share such characteristics as focus, willingness to take risks, persistence, originality, creativity, and a "peering over the horizon" potential. Since the program's start in 1981, the foundation has awarded about $200 million to 707 people (including this year's fellows) ranging in age from 18 to 82. MacArthur brainpickers chose recipients this year ranging from Pennsylvania pharmacist Michael Cohen, 61, who works to reduce preventable drug errors in health care, to Ann Arbor, Mich., violin maker Joseph Curtin, 52, who experiments with innovative strategies and materials to create a new breed of world-class violins.

Since 2001, Alsop, 48, has been the principal conductor of the Bournemouth Symphony Orchestra in Poole, England. Known, according to the MacArthur Fellows bio, for her ability to communicate with her orchestra and audiences and her dedication to demystifying challenging music for a wide range of audiences, she doubts the money will change her much. "I can't see that I'm going to be a much different person," says Alsop, who was named in July to become music director of the Baltimore Symphony Orchestra in 2007. (That job in Baltimore now? "I signed the contract," she says.)

In Charlottesville, Terry Belanger confesses that he not only saw the award coming, he couldn't keep it a secret. "There's a limit to the number of FedExes you can get from the MacArthur Foundation in September before students know what's going on," says Belanger, 64, a University of Virginia professor and rare-book preservationist who founded and heads the Rare Book School (RBS) -- a nonprofit institute dedicated to the history and safekeeping of rare manuscripts, prints and books.

Located in the basement of U-Va.'s Alderman Library, the RBS has 15,000 prints, 50,000 old books, a 20th-century reference library "on bookish subjects," old bookbinding equipment and old printing presses. Belanger started the RBS at Columbia University in 1983 and moved it to U-Va. in 1992; more than 4,000 students have studied preservation of what he calls "the bedrock for the humanities."

As for the money? The university has bailed him out many times with generous support -- sometimes literally, when pipes break and flood the RBS. "But I have to find between 20 to 30 percent of the money every year to keep this place going," he says. "It'll be nice to have a little more motor oil greasing the various things we do."

Lobster fisherman Ted Ames, 66, is working to save the coastal marine life of Maine. "It still hasn't sunk in," he says of the grant. "But it is perfectly all right with me."

He splits his year by season -- as a lobster fisherman in summer and a marine researcher and conservation activist in winter. "The fish aren't there anymore," says Ames, who uses his detailed studies of spawning, habitat and fishing patterns, combined with his surveys of anecdotal experiences of aging fishermen, to support a call for stewardship of marine resources.

"It isn't always possible to find foundations who want to make grants to a curmudgeon old fisherman," Ames says of the Penobscot East Resource Center he and wife Robin Alden founded to help renew the coastline's environment. "But now, full speed ahead."

And filmmaker Belzberg, 35, sat on that mattress in the store for an hour. The MacArthur call took five minutes; it took her three years to raise money for "Children Underground," her film about homeless children in Romania. "To be honest with you, with my bank account the way it is, I couldn't buy the bed I was sitting on," she says. "This provides the freedom from the daily struggle of wondering where the money's going to come from. And now I'll be able to get health insurance."

The 2005 MacArthur grant winners:

Marin Alsop, 48, symphony orchestra conductor, Denver and Poole, England.

Ted Ames, 66, lobsterman and conservationist, Stonington, Maine.

Terry Belanger, 64, rare book preservationist, Charlottesville.

Edet Belzberg, 35, documentary filmmaker, New York.

Majora Carter, 38, urban revitalization strategist, New York.

Lu Chen, 33, neurobiologist, Berkeley, Calif.

Michael Cohen, 61, pharmacist, Huntingdon Valley, Pa.

Joseph Curtin, 52, violin maker, Ann Arbor, Mich.

Aaron Dworkin, 35, music educator, Detroit.

Teresita Fernandez, 37, sculptor, New York.

Claire Gmachl, 38, laser physicist, Princeton, N.J.

Sue Goldie, 43, physician, Boston.

Steven Goodman, 48, conservation biologist, Chicago and Antananarivo, Madagascar.

Pehr Harbury, 40, biochemist, Palo Alto, Calif.

Nicole King, 35, molecular biologist, Berkeley, Calif.

Jon Kleinberg, 33, computer scientist, Ithaca, N.Y.

Jonathan Lethem, 41, novelist, New York.

Michael Manga, 37, geophysicist, Berkeley, Calif.

Todd Martinez, 37, theoretical chemist, Urbana, Ill.

Julie Mehretu, 34, painter, New York.

Kevin M. Murphy, 47, economist, Chicago.

Olufunmilayo Olopade, 48, oncologist, Chicago.

Fazel Sheikh, 40, photographer, Zurich, Switzerland.

Emily Thompson, 43, aural historian, San Diego.

Michael Walsh, 62, vehicle emissions specialist, Arlington.

Michael Walsh's efforts to reduce vehicle emissions and Marin Alsop's conducting prowess earned each $500,000, no strings attached, from the MacArthur Foundation.