Last month's issue of Discover Magazine featured the "Top 100 Science Stories of 2007," a look back at some of last year's important discoveries, developments, and advancements in scientific fields. Not surprisingly, a few of these stories were robotics-related; and one that I found particularly fascinating was titled "Robots Evolve and Learn How to Lie." In a swarm of robots, whose behavioral software was evolved by successive generations of natural selection, the tendency to deceive others for personal gain arose naturally in some of the robots. Of course, if this were the predominant outcome of natural selection, the species would fail. Thus, it's also interesting to note that altruism developed as well, allowing the swarm as a whole to survive.
Check out Discover. For a limited time, their online archive of articles (from 1992 up to the current news stand issue) is available for free, no subscription or registration necessary. Regardless, I urge you to pay for a subscription. It's a fine publication.
[Edit:] Found another article about this from New Scientist, with a few more details: