What for?
Maybe Wikipedia/Mediawiki developers are taking care of things in the next version of Mediawiki, but in the mean time smaller wikis are getting totally blasted with spam. This is totally wearing the wiki maintainers down and stifling creativity and constructivness with most of the energies spent on making repetitive rollbacking to non-spammed versions and IP blocking which is ineffective since the attacks come from multiple IPs. So this wikipage has been created to help those folks who are looking to control the amount of spam on their wiki.