Some analysts estimate as many as 10,000 new workers are hitting the retirement age of 65 every day—and that exodus will continue for the next 20 years. But guess what? Not all of them are retiring. Indeed, while many are leaving their traditional jobs, some are not heading to Golden Pond.

As members of the Baby Boom population prepare to retire, a growing number are not willing to just rest on their nest egg. A recent trend noted by Entrepreneur magazine shows that "would-be retirees are taking over the workforce.... some experts even expect a boom in entrepreneurship as healthcare reform takes effect."

Contrary to popularly held assumptions, it turns out that over the past decade or so, the highest rate of entrepreneurial activity belongs to the 55-64 age group, according to the Kauffman Foundation. The 20-34 age bracket, meanwhile, which is usually identified with swashbuckling and risk-taking youth (think Facebook and Google), has the lowest. Perhaps most surprising, this disparity occurred in the 11 years around the dot-com boom—when the young entrepreneurial upstart became a cultural icon.

"The fact that the largest age group of our population is also the most entrepreneurial bodes well for the United States' economic future," says Robert Litan, vice president of Research and Policy at the Kauffman Foundation. "This study shows how several other emerging trends, from job tenure to regulatory changes due to the current recession, should facilitate entrepreneurship in coming years."

This isn't exactly a brand new trend. It's been emerging through the recession. In 2009, self-employment rates for older workers continued to be higher than those for younger workers, according to the U.S. Bureau of Labor Statistics. Among the unincorporated, self-employment rates were 18.1 percent for those aged 65 years and older. Among the incorporated, self-employment rates were 7.7 percent for those aged 65 years and older.

"In this tough economy, people are fighting to find new ways to support their lifestyles," John Challenger, CEO of Challenger, Gray & Christmas, told "Necessity is the mother of invention. They're going out and starting businesses because the job market is so tight that they have no other choice."