This is a link to an important article about backing up data. I use PhotoShelter and it's a great service. All photographers should know about storage options and backing up their data. If you're a photographer, work must be backed up at least twice on hard drives. Yes it's costly, but necessary.
Studies have been done on the life span of CD's and they do deteriorate, the effect looks like color bands running through the image. The end result is no matter how good the CD, (gold) they don't last forever, and they can become scratched, rendered unreadable.
I started using hard drives long ago to back up my work instead. One primary back up and a secondary back up.
Digital imaging is a great medium, but nothing keeps like good old fashion film, which many of us no longer use, especially photojournalist who have a deadline everyday.
A few years ago I interned at the Los Angeles County Museum of at in their Photography Department. While there I asked a curator what would be the best format the safest way to store something. Their answer was simple, and from a simpler time.... graphite on paper, it lasts hundreds of years if stored properly. The answer always haunted me, oh the "good old days!"