According to the SFWA obituary:
Polish science fiction author Stanislaw Lem died in his home city of Krakow on Monday, March 27, 2006. He was 84.
It occurs to me, rather to my surprise, that I've actually read very little of Lem's work. Most of my strong admiration for him comes from having read The Cyberiad, which I loved (though presumably some of the credit for that should go to translator Michael Kandel); but somehow that never led to my reading most of Lem's other books, including his most famous books.
I suppose it's not too late for me to go read them. But I'm still sad to see him go.
Here are some other relevant pages and sites (stolen from Locus Online):