I'm trying to track down an anecdote that I read in a book once, but can't seem to locate now. It's about Garry Kasparov being invited to give a talk (I think) and after his talk the organizer says he would like to present a challenge to GK in the form of some boards set up on a table at the side of the room. Garry says that, regrettably, he won't be able to take part in the challenge, going on to say that he took a quick look at the board positions on his way in. He then proceeded to reel off not only the next move (as played) but when and where the games were played and by whom, thus demonstrating his prodigious memory for chess positions.

I probably have got some details wrong, but the essential idea is there. Does this story ring any bells? 

I believe he took a 4 position test for a German magazine (Der Spiegel?) and did very well but not perfectly.

...as I recall from reading his autobio.

http://www.chessbase.com/newsdetail.asp?newsid=7190

Oh, never mind the above link...

Still... it was fun to read. 

It was in "How Life Imitates Chess"

Thank you, Arctor!