The game is using 4xAA in 720p and 2xAA IN 1080p by the way. Uncharted was 'only' using 2xAA in 720p.
The problem with 'edges' are not caused by 'missing' AA, but rather by other problems, like selfshadows that are not done with 3D polygones, like Doom3 did, or a compressed bump mapping methode which causes flickering.
All you need is a different shadow technique and a high quality compression.
But anyway, the visuals are already overkill. It doesn't need any more improvements.
What it really needs are more true life effects, like dirt, car damage models, rain and snow and more smoke and fog effects.
Currently, the game is just a great awsome picture, a photorealistic pic. But when it starts to move, then you will have the feeling that it's just computer graphics because those elements are still missing. No life in the game!
And, to be true, the series already had some of those effects, like rain and wet tarmec and sparcles.
Hope, this will already come in Spec III.
Just a nice preview: The market place with snow and wet tarmec in the main menu is wonderful, beautiful and really stunning.