A plug all the way from Singapore! The image shows the implementation of the zFail stencil shadow volume using Direct3D. Shadows are becoming more of a basic requirement than mere eye candy in newer games. Implementing it isn't difficult, but doing it in a robust and efficient manner can be quite a challenge.
The top left image above shows accurate self-shadowing and shadowing of overlapping occluders. The top right image exposes the front faces of the shadow volume. The row in the middle shows the wireframe of the shadow volume and the capping geometries. The last row shows a clear view of the front and back capping of the shadow volume of a sphere.
Interested in learning more? By the time this gets posted as iotd on flipcode, an article about implementing shadow volume should surface at the hardcore game programming column of gamedev.net. Do take a look if you are interested :-)
Yen Kwoon, Hun