Most of the time when I'm out I'm shooting, my camera is in Av mode. I've selected the aperture size I want and I'm letting the camera decide on the correct shutter speed and ISO that are required to correctly expose the scene (the camera is on auto ISO with a max selected in the menu).
Obviously I want the lowest ISO possible with a shutter speed that's not likely to result in blur from the motion of the camera. Newer lenses have IS that provides several stops of stabilization; if the camera takes this into account, it could select a slower shutter speed and a lower ISO while maintaining the same exposure.
So, does the camera take this into account? I'm thinking if it doesn't, then it must be possible to get less-noisy images by setting the camera to manual and reducing the shutter speed and ISO slightly based on the cameras previous selections.