I was just reading an article in one of my women's magazines that talked about skin care and it mentioned that the skin doesn't actually prune or recede but gets puffed up, hydrated with water.
Our skin cells absorb a little bit of water when we soak too long in the tub and because this swelling layer of skin is connected underneath to tissue that does not swell, the skin buckles causing wrinkled fingers and toes.
And that this process takes about 15-20 minutes. Or in my son's case -- about 30 seconds. <img src="i/expressions/face-icon-small-smile.gif" border="0">