The free-market position has always been that minimum wage laws actually put people out of work by raising the marginal cost of employing a "marginal" employee. This helps deny to young, inexperienced, low-skilled workers those bottom couple of rungs on the employment ladder.
Article today in the Wall Street Journal relates to this, but the most important paragraph is the last one:
Sen. Harkin's proposal follows the progressive textbook method for raising wages: Just pass a law that makes employers pay more. Yet whether it's an increase in the minimum wage or an increase in the less-familiar tipped wage, the law of unintended consequences still applies.
Indeed.