I still haven't figured out who the blue dress is.
http://i1283.photobucket.com/albums/a555/kegas_76/blue_dress_zps950c857d.jpg
The hair seems too dark for Jane Foster. Also I'm not good with profiles, does that even look like Natalie Portman? Did she get recast? Obviously the hair is way to dark for Pepper Potts. Neither of these two are included in the cast on IMDB. The only other named female roll (other than the main 3: Black Widow, Maria Hill, Scarlet Witch) is Peggy Carter and well...
While the still image from the trailer leaves much to be desired in terms of clarity, Soo-hyun is the best physical match for the unnamed person in the trailer. Given that she's shown hanging out with the Avengers, it's safe to say that she has a large role to play in the movie, and that Marvel is keeping her identity and purpose a secret for now.
That's my $0.02, anyway...
Is it May yet?
You are correct sir, the Samsung extended trailer confirms that lady in the blue dress is indeed her. Good work.
Is this a real concept picture or fan made because The Vision looks pretty cool.
Just watched the trailer again and caught the shot of Loki's scepter from The Avengers, something I didn't notice before. Could it be what animates Ultron from Tony's scrapped suits?