This technique is not really brand new, but today was the first time I heard about it. Using Interior Mapping one can add a lot of detail to buildings which have been created from simple geometric primitives without creating additional geometry. All the work is done completely within the pixel shader.
This technique is especially useful for scenes which take place inside a large city for example. The buildings can be created completely from simple primitives. Besides the obvious elevation for artists, this also reduces the amount of geometry that has to be processed.
So no more totally reflective windows in the future, nice!