Here are a few other links with much deeper informations
Official Joomla! docs
Presentation at French Joomla! Day in Lyon
I live in Europe. Europe has 23 official languages. If you are going to create websites in regions like this, you have to think about multilingualism. Two things are especially challenging when it comes to creating multi-language websites: the translation of the static Joomla! text strings as well as the translation of the content items. While the first challenge can normally be overcome easily, the second one presents the real challenge.
The Joomla! 1.6 core is now available in 23 languages (February 2011). Joomla! 1.5 is available in 51 languages and more languages are expected to come soon. More than 50 languages are in preparation.
Let’s build a multi-language website by using Joomla! 1.6 core in this chapter.