If you do this it will probably mean offering the languages as either discrete archives, or one archive with all the languages.
This will also mean that each module/plug-in will have to package their own language files and place them under that modules directory (as some already do). Additionally the images for each module should be placed in a directory under that modules directory.
I think this will also make the installation of PostNuke a little easier because you add the extra features to the base, rather than downloading the base, remove the stuff you don't want and then upload to your live server.
This can also help when you want to remove a module, simply delete the entire directory for that module and it is gone. No more searching throughout your site for bits 'n' pieces
To please those that "want everything in one go", all packages could be placed in one master archive.
I realise that this all probably means more work for the developers at release time, but ultimately I think it will produce a nicer, more professional and user friendly distribution
Oh yeah, what you guys have done so far really rocks!!