CinemaBlend is now offering some tidbits of information concerning Thor 2. First they give the impression the film could be coming sooner than expected with a possible 2013 date opening the same summer as Iron Man 3. It sounds about right as Marvel has yet to announce a second 2013 film. They mention that possible villains could include Amora (The Enchantress) and Skurge (The Executioner) allies of Loki. Amora plays both sides working with and against Thor while trying to win his affection with magic and trickery. Skurge on the other hand is a bruiser warrior originally born in
Jotunheim (Frost Giant Realm).
Blend is usually on the money but things change as it's early in the development process. Previously they sited Fing Fang Foom, Ten Rings and Manderain as the villains in Iron Man 2 but that of course didn't turn out to be true. That being said the two a very likely going to be in future Thor films as they are centric characters but I wouldn't rule out non-Asgardian villains. Alice Eve has been linked previously to testing for different female roles and it's possible she very well could end up playing Amora. My hope is that the sequel is entirely set in the cosmic world giving us a better look at the mythology and the other realms.