Yeah, when I bought mine last year the previous owner/joker had switched them. Took me while to figure out why the rear backup light was so weak.
Of course, if you go to a country that drives on the other side of the road, they are reversed. It's a rear fog/parking light.
Slideshow: A one-of-one U.S.-spec Mercedes-Benz SLR McLaren Roadster became even rarer after a factory-backed transformation at McLaren's headquarters.