I connected the Xbox360 up via VGA and set it to 1920x1080. Success!
The KDL40W2000 *DOES* accept a 1080p signal over VGA, HOWEVER when it identifies itself over the VGA connection it does not specify this mode as being available, additionally it claims the mode is unsupported in a little message to the bottom right of the screen... which is CLEARLY nonsense because two clicks of the select button and it goes away leaving the Xbox360 picture in all its 1080p glory running perfectly well with what I will assume is 1:1 pixel mapping.
I have yet to experiment further, however; I am not entirely sure if the Xbox360 will let you CHANGE the VGA output to 1920x1080 when you connect it to a TV that does not specify it as available. I had connected mine previously to a Dell 2407WFP which had that mode, and then when I hooked it up to the Bravia it somehow seems to have remembered the setting and used it!