Thank you Rafael. Interesting.
Here is a link to
a list of applications that have popped up
as a result of the energy they have put into attracting developers. It pales in comparison to the tools available in OpenACS and a lot of the extensions from third parties could be easily adapted to work with dotLRN/OpenACS as well (if people are willing to pay the yearly licensing costs that help the developers pay to take part in the Bb developer community