I suppose you could have a function that fetches a string from a language file and returns it to your standard printf functions?
char * get_localized( const char * message, const char * localization)
where you put in some common message like CREATE_CHARACTER_SPIEL and localization like EN and you get a character creation spiel string from the english language pack back as a pointer to a string.
Such a system would make it easier to edit the things the game says without compiles. That'd be nifty.
The language packages would likely be organized into an associative array (easy to do with PHP, harder with c, STL maps for c++?)
Assuming you weren't going to drag STL into AFKMud how would you go about making the language files interact with the codebase? You could link them up as structs with key and value elements, but that'd be fairly slow I would think.