In Kevin Feige’s (Marvel Studios producer) most recent press conference, he revealed a few tidbits about the Thor adaptation.
Donald Blake shall not make an appearance in the movie, although it shall take place in contemporary Earth, rather than the Viking era. The film shall retain a Marvel superhero feel, rather than a fantasy-esque adventure.
As for the casting of Chris Hemsworth as Thor, Feige said, ‘There was no question’.