Exclusivly from AICN:
Thor
The film starts with the 6 warriors (Thor, Loki, the Warriors 3 and Sif) in Asgard, OdinHopkins on the throne, etc.
* Loki is adopted, hence the black hair.
* Loki kills his dad, usurping the throne, Thor is cast out to Earth.
* Thor lands in a desert, and is promptly run over (literally) by Natalie Portman and Stellan Skarsgard, a PhD cosmology student and her Norwegian professor, who have gone out to study though telescopes a strange cloud in the cosmos.
* When they realize that Thor is who he says he is, Stellan, who has grown up with Norse mythology, can't quite deal with it and goes out on a drinking binge.
* The script closes with a 5-page battle. The fighting styles for Thor and Loki are, as you'd expect, markedly different, Thor being very much about raw strength, Loki being much more about motion, grace and intelligence. The closing battle will be the first thing they film.
Avengers
* Loki is one of, if not the key [“Avengers”] bad guy.
* The [“Avengers”] film opens with 20 minutes of Loki basically entrapping/brainwashing Banner, and in so doing gaining control of the Hulk for his own nefarious deeds. This spurs the Avengers into existence.