The current issue of The Economist has an intersting article about biologically-inspired architecture:
So far, the use of biomimetic features in buildings has been driven as much by aesthetics as by function, and has been limited to relatively simple, passive systems. The Arab World Institute in Paris, for example, has an array of mechanical, eye-like irises on its south-facing facade. These open and close to control the amount of light entering the building, thereby regulating the internal temperature.
A quick search led me to this fantastic photograph of said mechanical irises, taken by Carlos E. Restrepo.