Is it possible to predict gender with a urine test?

I just read about a product called Intelligender. It claims to predict the gender of your unborn baby, from 8 weeks gestation forward, with 90% accuracy. First question: is that possible? If so, why hasn’t this test been offered before? And second question – is 90% accuracy good enough to spend $42.50 to find out your baby’s gender two months earlier than your normally scheduled ultrasound? What if it’s wrong?