I had to Google it! Never heard of it.. neat idea, but I would wonder if the formula wouldn't mix well since the water will be cold, also not a great idea given that powder formula is not sterile and should be made with water that is at least 70C. Even if you have an older infant and will be feeding right away and are willing to forgo the proper prep method, the bottle will be cold and need heating...
When I used powder, I used to have a thermos with warm water in it and kept the powder in a small Tupperware container... easy to toss together and shake. I only used powder for a month before finding the ease of liquid