Last week we edited and posted all of the videos from Joomla 3 Day.
One of my favorite sessions was from Ron van Schaik, who talked about how to build multi-lingual sites with Joomla 3.
Ron takes you through the process you'll need to follow, explaining each step carefully and pointing out common mistakes.
This really is a useful and comprehensive presentation. If you want to build a Joomla site in more than one language, you really should watch this video:
Ron also posted the slides for his talk: