Peer-to-peer groups with Paper Airplane

I've been meaning to blog about Paper Airplane since April when I first read about it at the Nanopublishing weblog, which got it from hatch.org: Flying the Two Way Web.

Technically, it's a Mozilla plug-in, but implementation details aside, what's intriguing about it is the way it builds on the P2P model to faciliate ad-hoc group formation:

Paper Airplane ... empowers people to easily create collaborative communities, known as Paper Airplane Groups, without setting up servers or spending money. It does this by integrating a web server into the browser itself, including tools to create collaborative online communities that are stored on the machine. Paper Airplane Groups are stored locally on a user's machine. A peer-to-peer network is created between all of the Paper Airplane nodes that are running in order to resolve group names, reach normally unreachable peers due to firewalls or NAT devices, and to replicate content.

To get an idea of how it works, look at this slideshow.