It used to be a given that a rise in temporary employment was a sign of economic recovery and that permanent hiring would not be far behind. In recent months, temporary hiring is on the rise, but the old pattern does not seem to be holding. Employers are not only keeping their temps longer, they're even using them for professional jobs and executive positions. The consequences could be very different at different ends of the income scale. We look at the potential consequences, which may be very different for blue-collar workers than they are for professionals or in the executive suites.