Here's the vid posted on the front page, about the new raid area: .
Now, at about 4:31 in the video, it shows a large room surrounded by lightning pillars, which looks like where the Thunder King fight will take place. At about 4:53 in the video, it shows a room with a huge lightning ball above the platform, which might be where the Ra-den fight takes place.
There are also two VERY strange looking statues of some type of creature's head, something I haven't seen in WoW before. I think it might be something Old God related. Is there a possibility Ra-den is Old God related?