Chipping away at Dave's version some more:
The OpenACS project is a vibrant and supportive open source
community cooperatively developing the Open
Architecture Community
System for the creation of dynamic web sites. We build software to enhance collaboration, communication, and
knowledge transfer.
OpenACS is a community-oriented,
localized, secure and scalable toolkit of reusable modules
around a stable core. OpenACS is freely distributed under the GPL.
/Bart