In reply to Harold Jarche » Born in a storm. Thanks to OS communitiesThanks Jon, we really enjoyed this project and it has taken us almost three years to get to this point, with a working CoP. Our clients are quite satisfied & excited with a January start to getting additional communities joining the system.
In the planning/prototyping process we went through a lot of different platforms, and open source software allowed us to change systems without cost over-runs. You have to note that the main community system, Elgg, didn't even exist when we started the project. Had we gone for a proprietary system initially, with up-front license costs, we would not have had the flexibility or resources to test out innovative new systems.
I have to really thank all the members of communities who have freely given of their time and with whom we have collaborated (or tested their products for free) over the past three years, in addition to the ones already listed::

Mambo
Drupal
Tiki Wiki
eGroupware
Liferay
BarnRaiser