.LRN (dotLRN) is an e-learning platform built upon openACS core. It includes 
modules and configurations that are specific for learning communities.

OpenACS (Open Architecture Community System) is a web application platform 
designed for high traffic community websites. It is built on a free and 
open source foundation. OpenACS is the foundation for many products 
and websites including the (www.dotlrn.org).

OpenACS runs on AOLserver and uses either the PostgreSQL or Oracle (which is 
not open-source) relational databases. It uses TCL as its main language. 
AOLserver, postgresql and Oracle are used in some of the most demanding, 
high-traffic web applications in the world.

WWW: http://dotlrn.org