One of my favorite Counter-terrorism Blogs, Global Guerrillas, posted a link to National Geographic's Introduction to Swarm Theory awhile back.
The article itself is good and worth reading.
But I also like the idea of someone out there smarter than I to apply swarm theory to a HIPS type product. Dave Aitel wrote of nematodes back in September 2005 and it didn't get a very warm reception. My gut reaction to these various articles is to implement a defensive swarm via a HIPS solution. Various hosts could form a hive, if you will, and touch each other frequently enough to get a group awareness of any threats they are seeing.
Based on the article the algorithms seem to already exist in at least some state; implementing them as a situationally aware defensive measure could be neat as hell.
I need to know more academic researchers so I can drink beer with them and shower ideas down.