Most impressive are :
- the membership allowing you to create an extranet,
- the "catagories" and areas of intrest meta data,
- the amazing number of ways to reuse content.
- and the plug-in architecture...
- oh yea, IT'S FREE!
There are still some bugs and the documentation is barebones. But the API is well organized and that makes it easier.
This free software has huge potential as a content management system for the corporate and government market.