For your interest, it looks like Apple has come to the party with a wiki of its own, without the need for people to learn markup language: http://www.apple.com/server/macosx/leopard/wikiserver.html
We've been using MediaWiki as our office intranet over the years but it's never been adopted to a level that we think it could be, because of the requirement that users learn wiki markup. For this reason we'll be ditching MediaWiki in our office next year for Apple's Wiki Server.
The reason I'm posting this is simply put forward the view that I hope WYSIWYG or some relevant variant will be developed for Wikimedia projects in the near future, because I think the hurdles that stop many people from participating on our office intranet apply equally to Wikimedia projects. And the hurdle is not that wiki markup is "difficult" or "hard to learn" but that it is intimidating and time- consuming to learn.
I have little doubt that one day using wiki markup only to edit websites like Wikipedia will be seen as an anachronism, even more so as other alternatives to MediaWiki (such as Apple's Wiki Server) come online, but there's a few hurdles to overcome yet and they're not all technical ones as far as I can work out.
It's always surprised me that WYSIWYG editing has not been made a high priority for Wikimedia, considering the fact that it was founded on the idea of broad participation. Although technical difficulties are often put forward as the reason, the biggest obstacle, it has often seemed to me, is an installed base of Wikipedians who see wiki markup as a way of protecting their territory and minimising participation by others. I've even had people argue that wiki markup is some kind of "intelligence" hurdle that people should have to overcome before being allowed to edit Wikimedia projects. Somehow this needs to be overcome if WYSIWYG is to gain traction and get a higher priority it seems to me.
Thanks to those who have been working on WYSIWYG for MediaWiki, particularly in trying to integrate FCKEditor, and I wish you well. However, if integrating an editor into the current environment is so difficult maybe there needs to be a new approach, such as developing new software/syntax with some type of WYSIWYG editor built in from the start? Worth a discussion at least, I should imagine.
Cheers, Christiaan
P.S. I originally posted this to mediawiki-l@wikimedia.org but that was probably the wrong list to post to.