The Register reports someone else reporting that the stability of data recorded on at least generic brands of CD-Rs is less than two years, even when treated reasonably. [Hmmm… is there a version of tar that does Reed-Solomon error correction?].
Three things about that –
The truly paranoid trust no single backup medium. Tape, spare IDE drive, CD-R, it’s all going to go bad sooner or later. (Tape sucks. Tape will always suck. But will always suck less than losing your data).
The most stable form of storage mankind seems to have invented is either Cuneiform (baked clay lasts a long time) or sticking bits on an interstellar probe (e.g., the recordings on the Voyagers). For good bit/century-scale retention, stone is also good, as is vellum (if you treat it well).
My prediction: Someone will try to prop up the saturated CD-R market with “certified life” products. Not a bad idea, really.