The wikis listed below use the MindTouch Deki wiki/collaboration platform – formerly known as DekiWiki, and currently known as MindTouch TCS (MindTouch Technical Communications Suite) – from MindTouch.com. The software is released for free under either the GNU General Public License (GPL) or the GNU Lesser General Public License (LGPL). 
From the website:
- What Is Your Business Wiki Strategy?
"Over 1,000,000 wikis are deployed within businesses. If you are not using wikis, your competitors probably are. Wikis enable businesses to innovate faster, operate more efficiently and increase profits.
How do you go from idea on Friday morning to global launch by Sunday with your team dispersed across four time zones? MindTouch pulled this off when we launched wiki.com. Our own product made this global launch possible – all within 72 hours. Now it's available to your company as a plug-and-play appliance for use as a simple, effective, smart Intranet.
Choose MindTouch. The proven, fully open standards based wiki solutions."