Originally Posted by sarf

As far as I know, Battlegrounds are for all intents and purposes normal maps, not instances. This allows you to use the regular "retrieve coordinates of raid members" routines, which allows you to do such an addon *right this minute*.

It would be quite neat, too, as my Cartographer quite often messes up in BGs (mostly AV) and hides all the raid members behind colorful flowers and veins.