These are not unique to WDW. You can find them in restaurants and clubs all over, and you can buy them on the internet, too. There are several different brands, and they can be found in solid colors, multicolor, steady on, and flashing.
Glowing Ice Cubes, Lighted Ice Cubes,Glow Sticks, Light Sticks Bright Light Up Ice Cubes - GP CrystalCube™ (Flashing Ice Cubes)