For a detailed description in English, see AVBOT: Detecting and fixing Vandalism in Wikipedia. CEPIS UPGRADE Vol. XII, No. 3, July 2011, pp. 67-70 (PDF link)
AVBOT is an anti-vandalism bot for Wikipedia projects (although it would be useful for all MediaWiki sites).
Its main developer is emijrp, a veteran user of Spanish Wikipedia. This project is in an advanced status, and it is used in Spanish Wikipedia under the nickname AVBOT with great results. You can see it running 24/7 or some of its clones. It has reverted more than 250,000 vandalisms.