apparently is just sodium polyacrylate, and when you put water into it, it turns into "snow"
yeah it works really well actually. We did this back in iowa for the last few years before i moved to CO.
Just get more then you think you need, we just got the 50 gallon bulk order. IF you are careful with your outdoor carpet you can roll up the snow after it dries out and turns back to powder so you can just add water and do it again later. If its windy the powder will blow away =(