Im not sure if it has been officially announced yet, but Ive read about some rumors that Thanos will be the villain of the Guardians of the Galaxy. Very good move on the part of Marvel if this is the case. Marvel/Whedon teased Thanos at the end of The Avengers and prompted non-nerds to look up the character and his history. Since the Guardians are a team that is based in outer space, and Thanos is all about outer space, it will be a great way to do a Thanos movie and establish him as a huge threat in The Avengers sequel. He should definitely be the main villain of the film. If the main villain of this film is someone who, like Loki in The Avengers, you find out is working at the behest of Thanos, then thats not really something Id be that interested in. Make it Thanos for 2 hours, and my ticket is sold.