Per Vin Diesel’s Facebook Fan Page: “The Riddick team is in New Zealand location scouting already… that’s exciting.”
Just a couple of of status updates below that, Diesel mentions that Twohy has already completed the script for the film. Progress!
But though there appears to be some forward movement on the sci-fi sequel, I wouldn’t expect anything official until Universal actually greenlights the thing and tosses these guys some money, neither of which have actually happened yet.