If this turns out to be true (and it may not), it would make some sense considering Thanos' main weapon is the Infinity Gauntlet. The Infinity Gauntlet shows up very quickly in "Thor" (it was one of the items in Odin's vault). The Infinity Gauntlet prop was also on display at the 2010 San Diego Comic Con. This may have been an Easter Egg leading to Thanos appearing in "The Avengers". It may still turn out to be false though so take this news with a grain of salt till the news is officially confirmed or debunked.
"The Avengers" will star Robert Downey Jr., Chris Evans, Chris Hemsworth, Mark Ruffalo, Samuel L. Jackson, Scarlett Johansson, Jeremy Renner, Cobie Smulders, Stellan Skarsgard, Clark Gregg and Tom Hiddleston. "The Avengers" will be directed by Joss Whedon and will be released May 4, 2012.
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