Installation of MediaWiki
The default installation will create your wiki in subdirectory /mediawiki. Should you wish to have another name, e.g. http://www.yourserver.com/wiki, then you must make two changes.
After installation of MediaWiki, your Wiki is available on every Virtual Host you run - unless you follow the instructions to place MediaWiki inside a Virtual Host.
An extra feature we added was support for iFrames by means of a little PHP script that we googled; the extension is called websiteFrame.php.
Furthermore, we changed the Creative Commons picture in the footer from a remote one to a local one.
One of the nice things about using something as popular as MediaWiki is the availability of a great number of extensions. One of the first things to do, therefor, is to install the default Debian Mediawiki Extensions package.
Multiple Wiki's on a single server
Some people want to run multiple Wiki instances on one single server - especially so if that server runs multiple websites (the forementioned Virtual Hosts). The answer to that is to create a Wikifarm.
Note that we've set up a separate site for this problem - you're welcome there with any questions you might have on wikifarms on Debian.