The "remove chromatic aberrations" function in Lightroom 4 never did a darn thing for me...I kept reading it was an amazing tool, alas, I couldn't get it it work. The recent 4.1 upgrade added "colour fringing correction"...a little eyedropper where you select a portion of the image that has a purple (or green) cast and voila! It cleans up the entire image. I'm thoroughly impressed and thrilled with this little addition. At work now, but will post examples later if anyone cares to see.