Vin Diesel has announced on his facebook page that the much mooted Riddick sequel is a go and gave some details.
The actor wrote, "[David Twohy] the writer/director just landed in New York with the good news. We can start filming this summer." He added, "However, there is a catch… in order for us to make a true R rated film, I must work for scale upfront." Meaning, the budget may be closer to the modest Pitch Black than the grandiose Chronicles of Riddick. Given how better the first film was that is not a bad thing.
I spoke to Diesel a month ago in Rio and he talked about the possibility of the harsher rating. You can see it below.