Fastmac.com has optical drives. I've been looking around and I guess apple may offer them in the future. I believe they have a keynote today regarding the new mac book designs... Maybe they will have something in there.
External would be good but it's not that covenient for me. I travel alot and I edit on the spot with a film crew. Editing in HD and exporting to blue ray would be nice. I guess now that I say it, external would be bad...find me some good prices