However, there are two important factors that go into determining if a product will whiten your teeth; Strength of the hydrogen peroxide and the contact time of the hydrogen peroxide on the teeth. Mouth rinses fail on fulfilling both of these criteria. The concentration of hydrogen peroxide is very low, it needs to be low, because if you swoosh and spit with a concentration strong enough to whiten your teeth in 30-60 seconds, you would burn a hole in your cheek. I am betting that the majority of people even have a difficult time with swooshing for the recommended minute.
I did have a patient tell me one time that he kept the stuff in his mouth for 15 minutes! There are easier ways to whiten you teeth :)
On the other hand, I am a fan of using hydrogen peroxide containing mouth rinses before I floss. I like the way the H2O2 bubbles around the gingival margin of the teeth capturing the plaque that is trapped between the teeth and under the gums as you floss. I also like to rinse with H2O2 containing mouthwashes before I use a tongue scraper, because as it bubbles it brings the bacteria up from the papilla of the tongue ready to be removed by the scraper.
Check out Discus Breath RX tongue scraper sold at drugstore.com and Listerine Whitening MouthWash pre-brush rinse sold pretty much everywhere.