reasonably common within organizations I've been at, though some have used Twiki or Plone or another one instead of MediaWiki. I advocate for it, and prefer using MediaWiki.
Just to give more clarity: I am more looking for benefits of wiki in general and not which tools to use because if we decide to use wiki then it will be mediawiki indeed. I think it is great platform!. So the question is not "Which wiki tool?" but "Why wiki (concept wisel)".
It wold be really nice if we can have a wiki page on the Internet, specifically targeted for conviencing executive managment and bosses (just like sometimes you have to convience them for using open source tools). This will really lead to quicker adoptation of wiki in corporate environment.
Thanks for the pointers tough.