My google alert for "open source cms" showed a discussion on i18n.
"Gábor Hojtsy shares his insights from comparing several open source CMSs, including Joomla!, Drupal, Plone and Typo3 specific to multilingual support..."
http://www.duesentrieb.org/2007/06/how-they-compare-multilingual-support.html
Has quite a lot of links from it, so be prepared for some good bedtime reading.