I just posted a paper on the Hiveworks.com site, discussing the application of the Ant Colony System meta-heuristic to the Traveling Salesman Problem.
This approach, first described by M. Dorigo in 1996, uses the emergence properties of real Ant Colonies, to solve hard optimization problems that cannot be efficiently solved by deterministic algorithms. Marco Dorigo, for his work on “Ant colony optimization and ant algorithms”, has been honoured with the first EU Marie Curie Award in recognition of world-class achievements in European research.

You can read my paper ‘Discussion on the implementation of the Ant Colony System for the Travelling Salesman Problem’, or visit the following sites:
Marco Dorigo’s homepage;
Ant Colony Optimization: a website dedicated on the theory and applications of the Ant Colony System;
EU Marie Curie Awards 2003.