Well I think water helps you get rid of RETAINING water, not precisely lose weight in and of itself. It's something to do with high sodium making your body hang on to more water than it needs, so when you begin to drink a lot it isn't afraid to let go of its stores.

As far as cold water burning calories, I think it's possible but I don't think it's quite the number they give. As we know, a "real" calorie (not the k-cals we are used to talking about) is the energy necessary to melt an ice cube. I'll bet the temperature difference between frozen water and newly melted water is more than or at least similar to the temperature difference between "cold" (less than 72 degrees) and body temperature (~98 for most). I don't see how heating 2 glasses of waters a mere 20 degrees could compare to melting about 25,000 ice cubes. However, I think water is good for you in so many other ways, and I think the research that has been done on controlled temperatures contributing to some weight gain (AC, or heat, keeping our bodies close to ideal temperature and therefore not shivering off or burning off as many calories over a lifetime) are interesting, so maybe the cold water is something to do with that.

I think Wyllen is on to something with the research! I also think 25 calories burned would be very difficult to measure in a controlled experiment.