So yet another cast member to add to the list which now includes Robert Downey Jr, Gwyneth Paltrow, Don Cheadle, Jon Favreau (who, of course, also directs), MIckey Rourke, Sam Rockwell, Samuel L. Jackson, Scarlett Johansson, Garry Shandling and John Slattery. As well as Clark Gregg who will reprise his role as Phil Coulson.
Mara, who you may remember from Brokeback Mountain (as Ledger's character's daughter) or Shooter, plays a character who's still under wraps. Of course she may not be playing a character from the comics at all but its always nice to speculate! Internet whispers suggest she may play Sharon Carter(S.H.I.E.L.D agent and girlfriend of Captain America) as a link to the Avengers movie. Personally (thought its highly unlikely) i hope she plays Jessica Drew!
No matter who she plays, there are certainly a lot of characters for Favreau to juggle in this movie, lets hope its not overkill. But im sure Fav knows what hes doing, and its likely a few of these characters may be glorified cameos anyway.