Interestingly, that page notes:

According to Microsoft programmer Raymond Chen on his blog The Old New Thing, Red moon desert was originally intended to be Windows XP's default wallpaper, but was allegedly changed due to some testers feeling it resembled a pair of buttocks, leading to O'Rear's other photo Bliss becoming the default wallpaper. While this wallpaper was temporarily set as the default wallpaper during Whistler, this story does not appear to be true; Bliss had already been selected based on extensive research by design manager Rob Girling and his team, and the Luna visual style shares the same color scheme as the wallpaper. It is more likely the wallpaper was set to default as a decoy; the unleaked Lab06 build 2415 predates build 2423, and shows Bliss set as the wallpaper.