The work ethic is alive and well among America's retirees, or at least the ones who bombarded me with letters after I suggested raising the retirement age for Social Security. They said they would be glad to keep working if I could find them a job. In theory, this shouldn't be a problem because employers ought to be clamoring for workers as baby boomers hit retirement age and the pool of younger workers shrinks. In reality, though, older workers face discrimination. While some companies are recruiting them, many employers are still leery, partly because of irrational prejudice against the old,...