This is a very minimum support to allow multilingual variables into Drupal core.
It does nothing by itself, just changes variable_get() function so any contributed module handling multilingual variables can define 'language_variable_init' function and throw its variables into the $conf array.
Also, it doesn't make any assumption about how this multilingual variables will be stored, updated or managed. It just tries to allow the feature without the 'dirty hacks' modules like i18n currently need to do for this.
If we had this in, we'd just need to add a language parameter to some variable_get() functions that need variables in other languages than page language, like the mail sending funcions... Provided there's a contrib module that handles them, they'll have their localized variables. Otherwise, nothing will happen.