I'm post this because I thought some of you might find this interesting.
Millenniata, Inc. (http://www.millenniata.com
) claims 1,000 year storage life on their special CD/DVD compatible media. I don't know about 1,000 years, but the study they reference from Naval Air Warfare Center at least seems to indicate that their proprietary media is probably much longer-lived than CDs or DVDs and less affected by environmental conditions. It does require their proprietary burner (about $2500 USD), but the disks can be read by standard CD/DVD readers.
The interesting thing about the Navy study (there is a download link on the web site) is that it showed great variation in CD/DVD writers, even within brands. It also showed great variation in CD/DVD media and that the most expensive brands were not necessarily the best. (To me this indicates a problem with "brand loyalty," since name-brand vendors are not necessarily the media manufacturers.) The study also said that different writers worked better with different brands of media.
Also, the results of the study reinforced the necessity to store your media in locations with proper environmental conditions.