In an online chat at Empire, Tom Hiddleston revealed when and where Marvel Studios will start filming Thor 2:
I have no idea. And without revealing too much, there's a specific skill set you need to be Loki's army - let me know if you have the qualifications. And all I know about Thor 2 is that we're supposed to film it in London in the summer and that it's being directed by Alan Taylor.
Walt Disney Pictures and Marvel Studios are planning a November 15, 2013 release for the sequel.