One of the strongest business cases for e-learning is for lowering training costs. That's why so many companies turn to e-learning, especially when they have ongoing programs, a large number of people to train or have a geographically dispersed workforce.
Let me know if you'll be in Boston for Drupalcon 2008 - I'd love to meet you. I'm on the planning committee for the event and am helping to organize. If you'll be in town, let me know, and I'll be happy to see you there! http://groups.drupal.org/boston2008