The Seattle Clojure group (http://seajure.github.com) has developed a unique style of collaborative interactive development I've termed "swarm coding". It involves a medium-to-small group with laptops all connected to a single host trading off on writing a small, focused piece of software.
This 80-minute unsession will begin with an explanation of swarm coding. We will discuss how to facilitate it at your own user groups, how to pick a project, and common pitfalls. Following this, we will break up into a number of smaller groups and each implement a small project.