AIR - screen

var screenArray:Array = Screen.screens;

for (var i:int = 0; i < screenArray.length; i++) {

 var screen:Screen = screenArray[i] as Screen;
 trace(screen.colorDepth);
 trace(screen.bounds.width);
 trace(screen.bounds.height);
}

From : http://www.r-stone.net/blogs/satoshi/2008/03/air.html