Flies can process a vast amount of information about proper motion and movement in their environment in real time - a feat that no computer, and certainly none the size of a fly's brain, can hope to match.
So it's no wonder that deciphering this system is a worth-while undertaking.
Visualizing retinotopic half-wave rectified input to the motion detection circuitry of Drosophila. Dierk F. Reiff, Johannes Plett, Marco Mank, Oliver Griesbeck, Alexander Borst. Nature Neuroscience, online publication from July 11, 2010.