From highdefdigest.com, specs are in -- and all good news!
Specs, Box Art Revealed for 'Dark City' Blu-ray | High-Def Digest
The short of things: BD-50, VC-1 encode, DTS-HD 7.1, Theatrical AND Director's cut (seamless branching), all original DVD supplements (including the Ebert commentary) plus additional commentaries (including Proyas, Goyer, and others) and other new extras.
Holy shit. As with DVD, New Line knows how to get it right and then some.