The article stated you should pixel map at least twice a year due to the fact that pixels located on your light sensor either malfunction, absorbing too much light causing "hot spots" on your images, or the pixels die, causing all kinds of optical aberrations. When you pixel map, the camera will identify these bad pixels and program around them resulting in a better image.
I had seen "pixel mapping" when I did other things in my camera's menu but was always afraid to mess with this function because I thought I would do irreparable damage. You seasoned professionals who read this will probably think it's silly that I didn't know what pixel mapping would do, but the manual is very vague about this function...as it is about a lot of functions the camera should be able to do. At any rate, for people like me who have never taken a course in digital camera mechanics, this is good news.
Photo credits: William Ardrey.