I remember how all the relics in Odin's Weapons Vault were explained expect for this one:
Since the beginning it was rumored that it was the Orb of Agamotto. One of the orb's main purpose is to teleport people, so perhaps this is what Odin used to send Thor to Earth (since the Bifröst was destroyed). Maybe that is the "dark matter the All-Father (Odin) had to conjure", as Loki mentioned. Anyway, the Orb is part of Dr. Strange's story line. Maybe the reason they never gave it the name of the relic in the first Thor movie was to protect any surprise appearances they had planned for this movie.
Well, we know that a Dr. Strange movie is "in the works" so perhaps he'll really show up. Set up the stage for his on movie.
That would be very welcome indeed then. My biggest gripe with the Avengers was how the magically brought Thor back with little explanation. So explaining that further in Thor 2 would be great and would solve one of my Avengers issues.
Still can't believe he never took off (even after the big fight) to see Jane though. He had time for shawarma