NEW YORK (FORTUNE) - Just when you think you're out, they pull you back in.

At least that's what most retiring baby boomers seem to want. In a new retirement study just released by Merrill Lynch, 71 percent of individuals surveyed indicated that an ideal retirement would involve working in some capacity, either part-time or in a new career entirely.

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"We find this very interesting," says Stephen Mitchell, who is a director in the Retirement Group at Merrill Lynch. Flexibility seems to be high on the wish list - respondents reported wanting to cycle between work and leisure time.

But those surveyed also said that they were looking for ways to either give back to their communities or pass on their hard-earned knowledge. "It demands that employers, the retirement industry and society turn the stereotypical notion of retirement on its head," Mitchell says.

With boomers facing retirement in increasingly large numbers, the issue is rapidly moving to the front burner. Unfortunately, employers seem to be slow on the uptake - according to the study, only 24 percent of companies surveyed said they were "on track" in their preparations to manage the outflow of talent, either by accommodating older employees, or by addressing the void they'll leave behind. And that, many experts suggest, could be a real problem.

"Workers ages 25-54 are a shrinking part of the workforce," explains Nancy Thompson of the AARP. "Brain drain is going to be a serious issue as boomers hit retirement age - our research shows that certain sectors will need to keep workers because there just isn't enough talent in the pipeline." The Merrill Lynch New Retirement Study, conducted by Harris Interactive, surveyed 5,111 working adults and over 1,000 U.S. companies with 100 or more employees.

This rallying cry is nothing new; management consultants have been singing the praises of older workers for years. But the Borders Group (Research) began to see the light only after some concerted due diligence of their own. "Our research clearly shows that our stores do much better when we have true diversity among our staff," says Ann Roman a spokesperson for the Ann Arbor, MI based book retailer.

Throw in a hefty helping of industry demographics - more than half of all books sold in the U.S. market are purchased by people 45 and older - and an opportunity was born. "Looking for older employees made sense - they love books and they connect with our customers."

Seven years ago, Borders began thinking of ways to attract or retain their older workers. "Flexible schedules, training and support were clearly important," says Roman.

Today, it seems to be working – more than 16 percent of Borders' workforce is over 50. And they're thriving. Perks for older workers include a 401(k) catch-up program, which allows participants to make larger contributions, and the opportunity to buy health care benefits at group rates for part time employees. Borders became part of the AARP Featured Employers Program, which encourages employers to hire and retain older workers, in 2005.

But for Stanley Consultants, a consulting engineering company based in Iowa, keeping older workers is simply business as usual. "We don't have a special program for our older workers," says Gregs Thomopulos, president and CEO, "Ours is a knowledge business - experience together with expertise are the two most valuable resources we can offer our clients."

Stanley Consultants provides engineering and construction services worldwide, consulting on everything from bridges, ports and planned communities to flood control projects and highway infrastructure. Replacing retirees with younger and cheaper engineers fresh out of school simply isn't ideal. "We look for ways to keep older members because we need them," says Thomopulos.

Among their strategies is a phased-retirement program which lets their members (Stanley is employee-owned) begin to craft a work schedule that meets their needs. Today, more than 75 percent of their retirees participate in the phased-retirement program, and more than 30 percent of their workforce is 50 or older. In 2005, Stanley was named AARP's Best Employer for Workers Over 50.

John Sayles had worked at Stanley almost for almost 40 years when he retired in 2003 at age 69. He had considered a typical retirement. "I had some jobs to do around the house - some volunteer committees, and of course, five kids and six grand-kids to visit," he laughs. "But I had sort of hoped to do something for the company."

The call came two weeks later, a special project cataloging reconstruction projects. In Iraq. It was a good fit - in his role as a principal planner, Sayles had deep knowledge of environmental assessments and site location studies. He took the job. "I spent nine weeks there."

Now, at age 72, Sayles takes on the occasional project, but is also "on-call", popping in as needed to consult on proposals and weigh in at meetings, all for an hourly rate. "It keeps you fresh and thinking," he says. He maintains a workstation and computer at the office, and feels welcome at any time. "I like the clients, I like the work. And, I like that they're keeping the light on for me."

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