The uncanny Photosketch tool was not the only magic software tool debuting at Siggraph Asia 2009. These amorphous volumes can magically throw three different object shadows, all thanks to a program called Shadow Art. See it in action here:

According to developers Niloy J. Mitra and Mark Pauly, Shadow Art is a tool to create abstract sculptures that can cast three different shadows, depending on the angle they are oriented against the a light source. These sculptures can be built in the physical world with any material, not only Lego, as well as used in 3D rendering programs to achieve the same effect. [Shadow Art via bldgblog]