Twitter's Official blog post about the new translated version of French language:
With the addition of the Spanish version of the site last month, many people have joined the conversations on Twitter. More and more people twittent outside the United States and we are now able to accommodate users of nearly 30 Francophone countries. It is now possible to change the language settings in French with the participation of translators who have helped turn Twitter into a platform for truly global communication.
The French twitteurs golds can already track people and companies they are familiar. Whether you attended or @ @ Lepicerie lopera for your gastronomic outings, you read @ lemondefr way to work or you listen @ theteenagers on the way home or you’re a fan of @ CanadiensMTL, there is a wealth of information useful to discover at any time.
To see Twitter in French, just check your settings and select “French” from the menu.
