djeps sends in this excerpt from the Physics arXiv Blog:
"Japanese scientists have built a cellular automaton from individual molecules that carries out huge numbers of calculations in parallel. ... At the heart of their experiment is a ring-like molecule called 2,3-dichloro-5,6-dicyano-p-benzoquinone, or DDQ. This has an unusual property: it can exist in four different conducting states, depending on the location of trapped electrons around the ring. What's more, it's possible to switch the molecule from one to state to another by zapping it with voltages of various different strengths using the tip of a scanning tunnelling microscope. It's even possible to bias the possible states that can form by placing the molecule in an electric field. Place two DDQ molecules next to each other and it's possible to make them connect. ... When one molecule changes its state, the change in configuration ripples from one molecule to the next, forming and reforming circuits as it travels."