Netflix has released two trailers ahead of the release of season four: one for an episode called Arkangel and the other for one called Crocodile. Arkangel, directed by Jodie Foster, seems particularly Black Mirror-ish...helicopter parenting x100 in a society where people live for hundreds of years.
Update: Here's the trailer for a third episode, Black Museum.
Update: Trailers for two more episodes:
Eventually they might tell us when the full episodes will be available on Netflix?
Update: Finally...a premiere date (Dec 29th) and a full trailer. (thx, david)