According to this site, there`s no such thing. Another myth shattered, but are they right?
http://www.madsci.org/posts/archives/aug97/866819368.Ns.r.html
I see nothing there that conflicts with what I thought everybody considered ‘photographic memory’ to be; simply an efficient way of organising memories.
My Maths teacher at school had ‘photographic memory’; she (claimed that she) could circle the page numbers of a text book with different coloured pens, then look at the pages, remembering their appearance (but not specifically reading anything on the pages), then ‘turn and read’ the pages in her mind at a later date.
Or to put it another way, my reading of that cite is that it’s saying “Hey, this car isn’t red, it’s only painted red”.
I had always heard that everyone has a photographic memeory, but some people don’t have any film in the camera <g>.
Nice one Joe; I can’t help thinking I’ve heard it somewhere before…
Wow, mangetout, you must have a photographic memory! 
Yeah, Joe said it, but it was, like, as if it was right there on the page already. Spooky man.