At the moment the interface for setting a locale for an alias limits it to a specific language, but we should provide a way for people to enter things such as countries and scripts. The database field is just a text field so we just need a way to actually pick the locales.
Country would be useful for artists which use a different name in different countries which use the same language (usually because of legal issues), whereas script would be useful to distinguish traditional and simplified Chinese and for transliterations. http://bugs.musicbrainz.org/ticket/820 also suggests encoding for things like ASCII versions of names (e.g. ü becomes ue in German).