[Update: We now know who the Thor 2 script writer will be. Click link for details.]
Chris Hemsworth's mighty Asgardian warrior will be back on the big screen in Thor 2, which is slated for theatrical release in 2013 - just a matter of under three months after his Avengers teammate, Tony Stark (Robert Downey Jr.), suits up again in Iron Man 3.
Similar to how Iron Man 1 & 2 helmer Jon Favreau won't be returning as director for the third film in that series, Thor's Kenneth Branagh won't be calling the shots on the sequel to his comic book flick. He is, however, expected to return in some capacity, probably as a producer.
Another solo adventure with Thor was always in the books for Marvel - even before the first film was released in theaters to generally good reviews and a (current) worldwide gross of just over $437 million. Now the studio's superior, Walt Disney Pictures, has officially settled on a July 26, 2013 release date for the followup.
Why exactly Branagh has selected to not return as director is anyone's guess at this point. There are already rumors circulating about a breakdown in negotiations over his contract - and, of course, the possibility that creative control became an issue (as has long been speculated about Favreau stepping aside from the third Iron Man picture).
Whatever "bad blood" there may or may not be between studio and filmmaker, it's seemingly not enough to ward off Branagh from serving as producer on Thor 2. That alone seems to imply that perhaps the Shakespeare aficionado just wasn't ready to jump right back and once again take on the difficult task of helming another big-budget, effects-heavy blockbuster - one that'll come with extra demands from devoted Thor comic book fans who have their own preconceived notions (or, rather, hopes) about where the sequel could and/or should go, in terms of storyline, villains, etc.
While most people agree that Thor was an overall good superhero tale, there was certainly room for improvement; seeing as that Thor 2 won't be affected by the Marvel movie universe shared continuity to the same degree as its predecessor, the sequel can instead put more effort towards character development and exploration of the vast Thor mythology. Obviously, that encompasses a good deal of story material to be potentially explored in the film, not least of which pertains to the items glimpsed in Odin's vault in Thor - which would also pave the way for additional Marvel characters to be introduced in the future.
One thing that ought to be mentioned: With The Avengers and The Amazing Spider-Man already scheduled for 2012 - and both Iron Man 3 and Thor 2 hitting theaters in 2013 - that presumably means that Captain America 2 won't arrive until Summer 2014. Sorry, fans of the patriotic First Avenger, but assuming you like the first Cap movie (which arrives in less than a month), you might have to wait a bit longer for his next adventure.
In the meantime, though, feel free to speculate in the comments section about who you'd like to see direct the Thor sequel, now that Branagh appears to be out of contention.
Captain America: The First Avenger hit theaters on July 22nd, 2011.
The Avengers arrives next year on May 4th, 2012.
Iron Man 3 will hit theaters on May 3rd, 2013, followed by Thor 2 on July 26th.
Source: Walt Disney Pictures/Marvel