Comic Con's been and gone now, and threw up what looks to be a roundabout confirmation of a second Darkness game from Top Cow. Not really sure how Starbreeze is involved, but there we are. From TheQuarterBin:
There is a Darkness video game sequel in the works. They made the announcement saying, “We can’t say Darkness and video game sequel in the same sentence. So, Darkness. Wink. Sequel.”
So there you have it. Hopefully this time it'll be more than walking around really slowly in deserted streets with a snake on your head.