Hi,
Attached is a patch to mediawiki that adds a new option $wgDontSaveIPs
What it does is allowing completely anonymous wikis by replacing the IP adress with 0.0.0.0.
(a bit background, there's a german campaign wirspeichernnicht.de, which wants to enforce a more anonymous web and provides a couple of descriptions how to disable ip saving in different apps - for mediawiki it tells to change the source, though I thought a clean option would be better: http://www.wirspeichernnicht.de/content/view/9/24/)
Attached patch is against mediawiki 1.15rc1. Would be nice if you would apply it.