After installing Freya beta, I set the language to french through the system prefs. After setting the locale and restarting, everything is not translated: e.g. the shutdown dialog is still in english, the sound/network applets are still in english, the Displays setting tool is still in english ("Displays" instead of something like "Écrans" or "Affichage"), etc.
Not long ago, I had installed an alpha version of Freya and upgraded it. I noticed that there were two different locale settings and while it was a mess, I think that using both of them allowed for a complete translation. So I guess the new locale settings tool doesn't set the locale everywhere needed. It might be the reason why Ubuntu still used the old gnome-languages-selector rather that GNOME's new prefs panel: I guess the latter doesn't set the locale everywhere needed for Ubuntu (and as elementaryOS is based on Ubuntu, this may be the origin of the similar problem).
Either that or translations are missing. Needs some research, but I can confirm that there are still untranslated strings all over freya. (shutdown, settings, some applications).