The rise of the permanently temporary worker

"Employers know that the economy could change at any time," says Jon Osborne, vice president for research at Staffing Industry Analysts, which follows temporary staffing agencies, "so by hiring somebody temporarily, companies have staffing for their peak needs but can let them go when they are no longer needed."

Companies stand to benefit from this flexibility, with the economy seesawing in the midst of a recovery that may take as long as five years. But it underscores the uncertainty for employees, with a huge number of workers -- 8.4 million -- reporting that they are involuntarily employed part-time, according to the latest federal statistics. Some of the underemployed are likely working for temporary agencies, while others are in informal settings.

Temporary workers are often paid less than full-time workers, and are not likely to receive any benefits. Such workers, according to a recent U.S. General Accountability Office report, are less likely to have health insurance or retirement benefits, or be protected by labor laws. Not providing health insurance means that ailing workers often rely on emergency room treatment or Medicaid, treatment scenarios in which the costs are largely covered by the public, adding to the taxpayer burden -- a charge, for example, that has been made against giant retailer Wal-Mart (WMT).