You can get any positions of any object, they're not stored locally.
To convert a position array you can use the mapGridPosition command.
Code:
_pos = mapGridPosition player;
hint format ["Map position: %1", _pos];
or
Code:
_pos = getPos player;
// _pos is now an array with [X,Y,Z] information.
_mapPos = mapGridPosition _pos;
hint format ["Map position: %1", _mapPos];
"Player" is local to each client. If you want to find the location of another object, just change player to whatever the name of the object you're trying to find is.
The grid position on the map is just a visual for players to make it easier to identify for themselves and others where they are. It's not what the engine uses for positions, and thus needs to be converted.