Without getting too deep into the Marvel Comics history of Thanos, this scene, albeit totally confusing to non-Marvel Comics fans, is important as it is likely teasing the villain for next years Thor 2. We know from Tom Hiddlestons interviews in promoting The Avengers, that Loki and Thor return to Asgard in the Thor sequel and theres a greater villain at play which just may force the (not by blood) brothers to work together. Its likely that Thanos will be coming to get at least one of the artifacts found in Odins Vault (image below), as shown in the first Thor film. Thanos needs the Infinity Gauntlet and Thor 2 must show him coming to get it. From there, Thanos will show up in Guardians of the Galaxy, a movie which remains unannounced but could come in 2014 or 2015, and if not, The Avengers 2, likely in 2015.