I turned on the TV and saw a new reality show with an intriguing premise: How big of a head start does a white woman need to outrun a black man? While skinny women frantically raced toward the finish line, a muscular black youth sportingly spotted them a 30-meter lead, then accelerated effortlessly and overtook all but the most desperately striding Russian woman. But this turned out to be the Olympic 800-meter race for women, even though the silver medalist, South Africa's Caster Semenya, is built like an LSU cornerback.  The Olympics have always had problems figuring out who should be ...