I've had a PS1 memory card die, it was one of those third party things with a button to select between several "virtual" memory cards on the same card. I didn't lose anything of value. After that however, I always keep backups over several cards. I always have at least two saves per game, and always save over the oldest one each time i save my game. That way, if i get a power failure I will never lose more than since last time I saved. Every every week or two, I also copy my most recent save for recently played games over on a different memory card.

Sort of related: You can back up your PS3 saves to a FAT32-formatted USB-drive, however the copying is really slow. I don't know why, but 15 MB isn't supposed to take 5 minutes.