So, TotalFilm has a brief interview with Eccleston (Malekith) which does a (very) little bit to pull back the fog surrounding the movie right now:
Eccleston describes Malekith as a bad guy with no redeeming features; he plans to take over the universe, egged on by Loki; he apparently likes the script; and, interestingly, the article concludes by saying that TDW will not only expand Thor's world, but also help set up Avengers 2.
As an Avenger fan (comics and movies) first and foremost, I'm wondering about that last line most of all. Does it simply mean putting Thor in place on Midgard for the necessary return to the Avengers? Or will plot elements of TDW actually carry over to Avengers 2? Possibly Surtur? More Dark Elf mischief? Or will the seeds of the Thanos story get planted in TDW?