After 20 years in the operating suite of a Dallas hospital, Hendrika deKorte, 82, now works half time. By Chris Mueller/Redux

Two years ago, Hendrika deKorte, a surgical nurse at a Dallas hospital, decided it was time to retire. But, she says, "they wouldn't let me go." Highly valued for her expertise in difficult specialties, deKorte agreed to stay if her hours were halved. "That's OK," says deKorte, at 82, Medical City Hospital's oldest employee. "I love my job."

The feeling is mutual, says deKorte's supervisor, Susan Hollingsworth. "We were more than happy to create a flexible schedule for her."

Skilled nurses like deKorte can dictate their terms because they're in such short supply. But a looming national brain drain—millions of unfilled jobs by 2010—is gradually easing the hiring market for older workers in general. If you have the right skills, or are willing to retrain, you may never have to retire until you're ready.

"Employers are smart. They're always looking around for the next untapped labor market," says Marci Pitt-Catsouphes, co-director of Boston College's Center on Aging & Work. "These days it's older workers."

People like Karen Tuttle, 61, a retired teacher turned CVS pharmacy technician. "I'd never even run a cash register or done anything but work with children," says Tuttle, of Springfield, Ohio, who took a short on-the-job training course and now checks orders, counts pills and advises customers on Medicare Part D. "The job changes every few hours, and everything I do I learned from scratch."

Despite the current uncertainty of the economy, a wave of retirements threatens both the public and private sectors. In the next five years, the federal government could lose more than one-third of its permanent full-time workforce.

In the private sector, health care, financial services, technology, social assistance, education, public utilities and engineering already report workplace shortages. So do trades such as carpentry, electrical work and plumbing.

Patrick Rafter, vice president of RetirementJobs.com, a Waltham, Mass., career website, adds more to the list: temporary professionals and administrative workers. "Those jobs are well suited for seasoned workers who want a flexible schedule," he adds. CVS even offers a "snowbird" option to more than 1,000 workers who shift between jobs in the North and the South.

Geography can be a major factor. "Commercial real estate is hot in the Southwest, and hospitality and tourism jobs are big in the Southeast, where hotels, casinos and theme parks need all kinds of workers," says Rafter. "In the South Central states, oil and gas industries need office support."

Transportation is another growth area. Jobs range from driving a delivery van (which requires only a license and a clean record) to handling heavy trucks on long hauls, which is how Jack and Eloise Murtaugh of Bel Air, Md., escaped from their high-pressure sales positions.

The Murtaughs wanted to travel, work together and earn good money in a second career. They discovered that two drivers operating a tractor-trailer can earn $48,500 to $57,500 per person a year. They investigated private truck-driving schools, but training costs ran $4,000 to $8,000 per person. Instead, they trained for free at Schneider National, a U.S. transportation provider, and now spend four to six weeks straight perched high in the cab of an 18-wheeler outfitted with bunk beds, a TV and a fridge.

"This is like one huge camping trip for us," says Eloise, 59. "We've seen the Grand Canyon at dawn and visited friends and family all over the U.S. We love being on the road."

Despite job openings in many fields, older workers still face daunting challenges: The Bureau of Labor Statistics reports 55-plus workers spend 22 weeks job-hunting compared with 16 weeks for younger workers. The Center for Retirement Research at Boston College reported last May that of 400 employers surveyed, many were "lukewarm" on providing ways for older workers to remain longer in the workplace.

But older workers can still win the talent race, says Linda Wiener, a Portland, Ore.-based workforce consultant. "Don't just think of job titles—that's too limiting. Think hot skill sets and hot industries, then connect the dots and see where you fit in," says Wiener, who is the age issues expert at the Internet job-search site Monster.com. "In the 21st-century marketplace, we've all got to be free agents."

Wiener says employers increasingly are seeking "soft skills"—computers initially screen electronic resumés for keywords like "communications skills" and "customer service." Mature workers are valued, she says, because they "can speak and write clearly, use good grammar—abilities younger workers may lack."

And older workers often have an innate sense about how to treat others, a talent critical to customer service jobs with good benefits and pay ranges of $30,000 to $50,000, says Joan Cirillo, executive director of Operation A.B.L.E. of Greater Boston, a nonprofit organization that trains older professional and low-income workers. "Businesses tell us they can teach workers proprietary software, but they can't teach them how to relate to a customer and let them down gently when problems arise."

John Rich, 80, of Wilton, Conn., says he uses his lifetime experience in sales and marketing in his full-time job at the Home Depot, manning the At-Home Services display. In his bright orange apron, he chats with passersby or roams the floor, looking for customers who might be interested in new windows, gutters, roofing and decks, then delivers his pitch—very successfully, he reports.

Besides customer service, technology skills are in hot demand. But knowledge of Microsoft Office, Excel and QuickBooks isn't enough, says Cirillo. "You've got to be able to navigate on the Net and toggle quickly between screens," she says. "You can't be hunting and pecking while a customer waits for an answer."

So important are tech skills that Robert Half International, a staffing and consulting firm in Menlo Park, Calif., offers free training to applicants for white-collar temporary and project management jobs in accounting, law, finance, marketing and the creative fields. "We actively recruit mature workers and we find that free skills training is a way to attract them," says Reesa Staten, company spokeswoman. "As soon as they register with us, we give them an access code and they can train on a home computer."

Many "recareering" midlife adults are turning to adult education, community colleges and other one- or two-year programs to brush up skills or learn new ones. Former data analyst Art Nied, 51, of Irvine, Calif., spent two years studying aviation technology at Orange Coast College and recently landed his dream job repairing $50 million luxury private aircraft.

"Even as a kid, I was enthralled with single-engine planes," says Nied. "I never expect to get rich, and I'll probably make one-third of what I was paid in my previous career. But I love turning a wrench and making something work."

Among state-sponsored training courses and resources for older workers, Arizona is leading the way, with the launch this spring of an online mature worker job bank for posting of jobs and resumés, and with the opening of career transition centers in the Tucson and Phoenix areas. The state also offers businesses a "mature-worker friendly" certification, similar to a Good Housekeeping Seal of Approval, if they meet set standards on workplace flexibility and training. "Our goal is to have every business in the state be mature-worker friendly," says Melanie Starns, director of the Governor's Office on Aging.

Eight other states—Alabama, Arkansas, Colorado, Florida, Maine, New Mexico, Ohio and Wyoming—are working with the National Governors Association to come up with ways to retain or lure back older workers.

In the next 10 years, the number of 55-plus workers is expected to grow at more than five times the rate of the overall workforce, the Bureau of Labor Statistics reported in December. In 2006, 29 percent of people in their late 60s were working, compared with 18.4 percent in 1985.

When Medical City Hospital threw a party for Hendrika deKorte's 80th birthday, her supervisor checked with parent Hospital Corporation of America to see if she was the company's oldest employee. Not even close. Of the 190 HCA hospitals nationwide there were no fewer than 60 employees who were older than deKorte.

Elizabeth Pope, based in Portland, Maine, covers work and retirement for national publications.