Science & Technology at Scientific American.com: DNA Computer Plays Complete Game of Tic-Tac-Toe
The human body, hell, even a bacterium, has computing capacity so vast that it makes our current level of computer power seem more like a pocket calculator from the 1980s. Our neurons, cells and even intracellular material have, in computer hardware contexts, tiny footprints and incomparable versatility. However none of this has been accessible to engineers, because while you can get a huge button the size of a finger (like those on your computer keyboard) to connect to a smaller wire, to connect to a smaller circuit (and so on (and so on (and so on))) until you pass the clicking of that button down to the smallest "circuitry" that is the stuff of DNA, no one has figured out a way to create or use collections of DNA in any way comparable to the structures of our current silicon "gates", which make up the foundation of our computer technology.
I have been following articles researching the use of this basic stuff of life for computer purposes for a few years. This article shows what appears to be a milestone in this arena. They have managed to get little puddles of DNA strands to play Tic-Tac-Toe, and win or draw every time.
This should force the vernacular to change the definition of "software". Or maybe they'll call it "squishware", though I haven't ever actually touched a puddle of DNA before.