This is probably the cutest experimental setting I read about the last few months (I do know that I have a particular understanding of what cute is).
Robots, disguised as cockroaches by simple pheromone coating, to make them look like cockroaches, that is at the chemotactility space. Then introduced in a group, to influence dynamically the collective decision-making process. And that works nicely.

More interesting the fact that the programming of robots wasn’t rigid, so they were influenced by natural individual and acted socially in opposition with their individual preferences.

Autonomous artifacts cooperating with living individuals to solve problems. Far away yet from Asimov’s robots, but on the right path.
Now, who wouldn’t like to play with such a setting?

Social Integration of Robots into Groups of Cockroaches to Control Self-Organized Choices
J. Halloy, G. Sempo, G. Caprari, C. Rivault, M. Asadpour, F. Tâche, I. Saïd, V. Durier, S. Canonge, J. M. Amé, C. Detrain, N. Correll, A. Martinoli, F. Mondada, R. Siegwart, J. L. Deneubourg
Science 16 November 2007: Vol. 318. no. 5853, pp. 1155 – 1158 DOI: 10.1126/science.1144259

Collective behavior based on self-organization has been shown in group-living animals from insects to vertebrates. These findings have stimulated engineers to investigate approaches for the coordination of autonomous multirobot systems based on self-organization. In this experimental study, we show collective decision-making by mixed groups of cockroaches and socially integrated autonomous robots, leading to shared shelter selection. Individuals, natural or artificial, are perceived as equivalent, and the collective decision emerges from nonlinear feedbacks based on local interactions. Even when in the minority, robots can modulate the collective decision-making process and produce a global pattern not observed in their absence. These results demonstrate the possibility of using intelligent autonomous devices to study and control self-organized behavioral patterns in group-living animals.