If you look closely, you'll notice that, given the orientation of the cube, its shadow is 45 degrees out of true. In addition, the glint of light reflecting off the cube suggests that the sun is in the wrong place to cast the shadow there anyway. This isn't a bug, it's a feature. No, really. We used a three dimensional cube on the cover but in reality OLAP cubes can have many more dimensions. We considered using a tesseract (a 4-dimensional cube) but that still didn't feel multi dimensional enough. In the end we decided to try to make the 3-D cube look subtly spooky by making it interact with light in an unusual way. It would be interesting to know how many people notice...