"Scoop is a "collaborative media application". It falls somewhere between a content management system, a web bulletin board system, and a weblog. Scoop is designed to enable your website to become a community. It empowers your visitors to be the producers of the site, contributing news and discussion, and making sure that the signal remains high."
Scoop is the backend of HuSi and some other sites (kuro5hin.org, dailyKoS). It's written in Perl and is the creation of Rusty Foster, with lots of help from others. The latest version of the code, along with news and discussion about features and bugs and announcements of new Scoop-based sites, can be found at http://scoop.kuro5hin.org/