You're thinking, yeah, yeah, seen it before. It isn't that hard to do. You select an area and desaturate the color in that area. It seems to be a lot of folks' favorite image editing trick. But that's not what's going on here.
If you follow the link back to her Flickr photostream, you'll see several other angles on the same people, including one taken for the San Francisco Chronicle. It's a gray Santa suit, a gray wig, gray body paint, and gray contact lenses. you have to get really close in to see the only color she couldn't cover, the pink corners of her eyes.