Yah, I've heard that, but it doesn't make any sense thermodynamically. I haven't tried it myself yet. But there are a lot of things in thermodynamics that don't make sense.

It does remind me of an interesting thing that happened last winter. My wife had left a nalgene bottle full of water out of our Brita filter in the car. It was around 0 degrees out. She brought the bottle to me and wondered why it hadn't frozen. I opened it, and it froze instantly. Supercooling is so cool!