I'm guessing that putting your face in positions your shoulders correctly? My understanding is that in cold water, you should try to conserve energy as much as possible by moving as little as possible. Getting out would obviously be the immediate goal but this technique could come in handy if you cramp up or something. (Best bet, of course, is not to fall in in the first place and be wearing a PFD if you do!)

(BTW - why is it that on every fishing tv show, nobody wears their life jackets, except the odd one with the cool self-inflating ones. Whatever happened to lead by example?)