all very good guesses so far. you're all on the right track. (hints start out vague and will get progressively more specific ;-)) here's the first hint.
The "mystery" image is a 100% crop from the original. I do use a reverse-lens setup for macroing, however. (my lenses are anything but macro - I think the closest focus distance is like 18 inches) With the reversed-lens I'm about 1/2 to 1/4 inch away from my subject.
I did a quick search for a how-to on the reversed lens but it looks like you replied to that thread. So I won't explain it here ;-)
ok, the picture really isn't very good, it was for first shot at the reversed lense gig and I really need to work at it. Can you say out of focus, it obviously in my vocabulary!