This has been one of those counter-intuitive anecdotal stories for a long time: that warmer water will freeze more quickly under the same conditions than cooler water. Seems crazy, right? The effect (it even has a name: the Mpemba paradox) seems to break the laws of thermodynamics, since it should take longer to remove more energy from the same mass. But scientists at Cornell have finally figured it out.
You can read their paper here, but the short answer is that they have demonstrated the effect whereby because of the way energy is stored in the molecular bonds of water, the hotter the water is when cooling starts, the faster it will release that energy.
Now, we just need to see if this works for beer.