So here's the deal, Nigel Cook gave a conference about the MCU today at the Disney Consumer Show 2013 in Mexico City. He talked about Iron Man 3 and show the same Iron man 3 trailer we all have seen many times. Then he start talking about Thor: the Dark World, he then smiled and said: " Here's the trailer". Now, the people who claim to have seen the trailer gives a very vague and brief description but gives detail of some scenes that will appear in the trailer, also they say that it doesnt look anything like the set photos we've been seen before and that it looks AWESOME.
It starts with a voiceover, is Thor, you see some scenes of a big battle and then Jane Foster and other humans running scared cause something is "coming". Thor says: "I promised I would return for you" as we see Thor arriving Earth to take Jane to Asgard.
Apparently the fight scenes are pretty awesome, and the trailer show that Thor is out of Malekith's league, in fact we can see a very damaged and tired God of Thunder. And since he's no match for the Dark Elve, the mighty Avenger will have to search for help. This lead us to a scene where we see a big crystal prision and there's someone sit on the ground. It's Loki.
Thor says: I need your help, but if you betray me…I will kill you. Loki smiles and answers: What do I have to do?
Then we see another scene of Thor figthing Malekith while Jane is watching. Malekith looks threatening. Jane looks terrified. Thor looks overwhelmed. Malekith stares at Jane and Thor yells: NOOOOO!
That's all we have until now, but, according to Nigel Cook we'll be able to see the trailer within 15 days and it will be screened before Iron Man 3.