When I used GameSalad what I would do is load a piece of art that was double the intended size and then shrink it down to the size i wanted. This shrinking down effectively insured that graphic would appear as retina quality.
Being this is an HTML5 game engine at it's heart, I wondered if this is how things are handled. I'm working in HTML5 exclusively now to understand the game engine, but i figured it would be good to know this now as i develop and import various art for the game.
I realize that this approach for web and mobile might not be the most efficient for web since most pc screens would not benefit from the denser graphics (maybe retina macbooks would) so yea just curious what's the best practice for dealing with graphics.
My hope is to make this game for all available mobile / tablet platforms, but i like the idea of it also being for web as well.