Good idea when user can choose Coppermine interface language personally.
I believe this hack has been posted...and will be in future versions of the standalone version.
- as a side note not the phpnuke version of coppermine has this feature built in thanks to phpnuke and the Language Specialists(translators) here. RC3 will be coming any day so if you decide to upgrade, you should wait for it...
A demo is available here:
http://coppermine.findhere.org/
It's here (http://forum.coppermine-gallery.net/index.php?topic=621)