We've recently added a ton of new functionality to our online education system edu 2.0, bringing the total code base to a whopping 25,000 lines of Ruby. The back-end architecture is also maturing, and uses the following components:
Sphinx text search engine and thinking_sphinx gem.
Automatic forum and message translation using Google translate.
Incremental backup system.
Our roadmap for 2009 is very ambitious, and includes launching a commercial version (edu 2.0 for business) in Q1, support for audio and video recording from your browser, offline support, mobile phone access, SMS integration, and seamless integration with a 3D virtual world.