If you don't mind not having snapping enabled, you can already create and use isometric maps like the one Patrick linked to. (Just make sure the grid's also disabled in your page settings) Enabling some sort of isometric snapping would be really tricky, I would think, for tokens. Tokens sitting on an isometric map tend to take up two or more squares in height. Since everything snaps to the center of the graphic, I'd suspect tokens would snap in really undesired locations on the map.
