The latest release of the free LetterMeister word game now allows you to play the game in French (as well as Spanish and English).
Go to the LetterMeister home page (see the link above) to download version 0.6b of the game. To select French as the language, go to the Startup Options dialog from the File menu. You will need to restart the game for the language change to take effect.
An update to the LetterMeister word game for iPhone is due to be released during early August that will also feature Spanish and French.