I work in a small post-production studio and we use DVD media for archival purposes every day. Our brand of choice for Data archive is Verbatim's little known 'MediDisc' line of DVD media. This media is DICOM certified for use in long-term medical records storage (including medical imaging) for compliance with HIPPA requirements.
Yes, the media is significantly more expensive than the consumer-grade 100pk DVD-R/ R spindles typically available at retailers such as WalMart & Best Buy, but is saving a buck really worth it when it comes to long-term data integrity?
Furthermore, we store the DVD discs in Tyvek disc envelopes (the same that Apple is now using for software distribution in packages such as Final Cut Pro HD) and place them upright in a light-tight storage container. Tyvek envelopes are currently regarded as the best storage option for protection of CD/DVD recordable media. Information Packaging is a good source for these envelopes.
I'll update with supplier information as I uncover it. I think the market for longlife media is going to improve quickly.