Joomla! 1.7 stable!
If you are using Joomla! 1.7+ stop right here. Joomla! 1.7 is now equiped with a language selector tool like Multilang M17n. The objectives of Multilang M17n are now part of the core of Joomla! 1.7+
Please read this carefully: http://community.joomla.org/blogs/community/1468-multilang-in-17-whats-new.html
The new joomla 1.6 possibilities on mulitlingalisation of your website are just not enough to have your website a true multilingial one. G17l is busy creating some tool to get the same functionality in 1.6 as you have with the Multilang M17n extension in Joomla 1.5. We are testing!