I have mentioned previously that I researched different wikis for my website and I wanted to share my experience. Today I'll talk about MediaWiki. I was aware of it for a long time (thanks to Wikipedia) and was seriously considering using it. MediaWiki is built on PHP and designed to use MySQL on the backend.
It is very mature, but in my opinion some of the features could be better implemented. The user base is quite large and releases happen often. I know it is scalable (not that it's important for me right now) since Wikipedia is one of the largest (if not the largest) wikis on the web.
The biggest problem with MediaWiki, for me, lies with technologies it uses. I'm not experienced with PHP or MySQL and don't really want to learn them right now. It might be easy to use, but in my experience web applications often require me to look at the source code to configure, customize or fix a problem with the application.
The wiki has export functionality, but it exports in wiki text format. I would prefer something better structured, like XML. It might be possible to export data from generated HTML, but that, most likely, would require writing my own PHP script.
MediaWiki has a number of useful features. It supports authentication, but number of roles is limited and permissions are set for the whole wiki, not individual pages. At least it's possible to let only registered people edit pages and track changes on individual basis.
Table of contents is built automatically for the page from headers. The page editor, while better that simple text area, leaves a lot to be desired for, especially from such mature project. There's a good support for image attachments.
The most unique feature is support for forum-like discussion on each page. I think it's a great idea. Too bad MediaWiki is the only wiki supporting this (as far as I know).
Conclusion
I decided not to use MediaWiki. I'm not familiar with technologies it is built on and I probably will have to spend more time trying to customize it than I want to. Export capabilities are also somewhat limited.
It is a good wiki, probably the best built on PHP. It has nice features, such as authentication and page discussion. It's just not quite what I was looking for.