Until now, French mac users had severe difficulties joining public wi-fi networks. Reason? For years, the Airport cards sold in France were limited to four channels. A restriction required by a local legislation (no longer active today; that's why it doesn't apply to AirPort Extreme cards).
Most of users thought the limitation was hardware. It was not! With the AirPort 3.3 update, all the channels are now available in the first generation cards. To check this:
Mac OS X Hints
http://hints.macworld.com/article.php?story=20040129093619671