The Bond director (Goldeneye, Casino Royale) is in talks, according to Variety.

Confirming he had been approached for the role, the Quantum of Solace star joked it would have been too much being both Bond and Thor:

“I would have been on some stupid power trip. Blonde hair and a big hammer? I can’t do it.”

Thor, reportedly to be directed by Kenneth Branagh, is set for release in July 2010.

Columbia Pictures has assigned The Office producers Lee Eisenberg and Gene Stupnitsky to write a script, according to Variety: Link.
The script will be completed before any of the original cast are asked to sign up.

Writer and star of the previous movies Harold Ramis confirms:

Yes, Columbia is developing a script for GB3 with my Year One writing partners, Gene Stupnitsky and Lee Eisenberg. Judd Apatow is co-producing Year One and has made several other films for Sony, so of course the studio is hoping to tap into some of the same acting talent. Aykroyd, Ivan Reitman and I are consulting at this point, and according to Dan, Bill Murray is willing to be involved on some level. He did record his dialogue for the new Ghostbusters video game, as did Danny and I, and Ernie Hudson. The concept is that the old Ghostbusters would appear in the film in some mentor capacity. Not much else to say at this point. Everyone is confident a decent script can be written and i guess we’ll take it from there.
Source: http://featuresblogs.chicagotribune.com/entertainment_popmachine/

“‘Superman’ didn’t quite work as a film in the way that we wanted it to…It didn’t position the character the way he needed to be positioned. Had ‘Superman’ worked in 2006, we would have had a movie for Christmas of this year or 2009. But now the plan is just to reintroduce Superman without regard to a Batman and Superman movie at all.”
Source: http://online.wsj.com/article/SB121936107614461929.html

(also ruling out any crossover movie).

“We’re going to try to go dark to the extent that the characters allow it”, Robinov adds.

To be played by Sam Witwer – BSG’s Crashdown, and Vader’s apprentice in the new Force Unleashed game.
Source: http://www.movieweb.com/tv/news/24/29424.php

Source
TV Guide magazine quotes original JP star Laura Dern:
“It’s a while away but my understanding is it’s happening and my character is very involved. I know [director] Steven Spielberg is looking forward to [getting it together] over the next year.”