I don't know what to make of it.
HOWEVER, I have a friend whose dau took a similar photo!
They were on a road trip. She took a photo of a field and out popped this photo with a faint image very much like the one in your link! However, in this case, the lady appeared in the sky...looked similar though.
These folks are NOT Catholic and are not very religious...go to church mostly twice a year.
Anyway, she showed it to the local priest who immediately asked for copies.
I have not heard that she is/was selling it on ebay or selling it anywhere.
In fact, mom and dau were just puzzeled.
She doesn't know if it was some kind of weird photo mess up at the lab or not. My gut feeling is that it was not done intentionally. They were too shocked. They were asking everyone if they had an explanation for it.
Regardless...whether it was divine intervention or some mix up in a lab....it was thought provoking. This happened about 8 years ago and I remember vividly.
p.s. I can tell you if this happened to me, I think I would be a little freaked out!