Reel DVD has released Dark City on Blu-ray. In addition to providing a ten minute longer Director’s Cut version, the Blu-ray offers amongst the greatest picture quality improvement I’ve seen from the format over DVD.
UPDATE (Saturday, 21 February 2009, 11:16 pm): I forgot to mention: rather than using seamless branching, the two versions of the movie are both encoded entirely separately onto the disc. That’s why there are so many commentary tracks: two are for one version and three are for the other.