This is something that other people have asked for before and the best way to do it is to integrate a wiki with a CMS.  Deki Wiki has a robust API that allows you to integrate with external systems and applications so you would be able to tie in the mediation process from the CMS into Deki Wiki. 

I saw the requirements that you posted in your other forum post too and I will address how Deki Wiki fits in them:

1. Mediation : All submissions from users are reviewed by one or more persons, with the proviledge to approve the publishing of a submitted document.

This would be accomplished by integrating with a CMS

2. Traceability : Any addition can be traced ack to the original contributor

Deki Wiki has a full audit trail of all changes to the wikis along with document versioning. 

3. Runs on the .NET platform.

Deki Wiki runs on Mono(the open source .Net)and also is compatible on .Net 2.0 or higher. 

4. Uses an SQL Server 2000 or later / MSDE database

Deki Wiki currently only support MySQL for its Database

5. Open source

Deki Wiki is open source with over 2,000 downloads a day.  Deki Wiki is also commercially backed by MindTouch with options for support plans.


If you have any other questions please feel free to contact us here: http://wiki.mindtouch.com/support