In the past, Blender used EnvMaps (environmental maps) in order to simulate the reflectiveness of objects. But this way was quite difficult, needing the use of Empties (null objects) and layers when a simple reflecting plane was needed. Fortunately, including Raytracing into the renderer eased the whole process and helped to achieve a greater realism.

Fresnel effect demonstration - pay attention to the ground reflections

For Blender: 2.50 Alpha 2 or better