For decades, the wealthy have summered in places like Martha's Vineyard and wintered in Palm Beach, while less-affluent retirees have made annual migrations north and south. However, as large numbers of baby boomers have begun buying second homes, a new trend is emerging.  Today in vacation-home hotspots like Cancun, Mexico, a new species of homeowner has been spotted-one that some demographers are calling "splitters."

The term stems from research done by a Florida home builder. It found that boomers are buying second homes at younger ages (47, on average) than their parents did and visiting them more frequently (18 times a year, according to the study). More important, they're finding ways to use their second homes for both work and play, which allows them to extend their stays. Some of these dual homeowners are migrating so fluidly between houses that terms like "primary residence" and "vacation home are becoming separate-but-equal residences.   Although this is a trend limited to an elite group with flexible jobs and enough income to afford two homes, many forecasters expect the movement to grow, especially as more boomers become empty nesters. According to the National Association of Realtors, 7 percent of baby boomers already own a vacation home, and some trend watchers expect that number to exceed 20 percent within a decade.

The splitter trend is driven by at least three forces. Technology is the most obvious one. The Internet, BlackBerrys and cell phones allow many professionals to work almost anywhere. The changing nature of jobs is also a factor. Compared with their parents, more boomers are self-employed (eliminating the need to ration vacation days) or work in jobs that require such frequent travel (like sales or consulting) that it hardly matters where they go home on weekends. The third factor fairly reasonable travel costs. Low-fare airlines, along with cost-saving Web sites like Travelocity, are key reasons dual homeowners are going back and forth more often.

As older boomers downsize, some forecasters say splitting may be an attractive option. Baby boomers have rewritten the rules for almost every aspect of life, why should retirement be any different?