Jim, since I make my moola by licensing copyrighted images I am senstitive to the issue of unauthorized use, and yes, this is only on my desktop. In fact, I was wondering how a person might copyright this particular image, since it is a tie-dyed pattern that resembles a water-color wash (I think that is what it is called...). I'm not even sure that it would be possible to copyright such a thing.
Anyhoo, if I was contemplating any use covered by the copyright laws (which I have successfully used to extract payment from people who have used my images without permission) you can be assured that I would contact the webmaster regarding my plans.
I may be wrong, but judging from the website I wouldn't be surprised if the background was "borrowed" from somewhere else. There are no copyright notices and the website appears to be non-commercial in nature.