Edit: Here is a video walk-through of the bunker!
https://www.youtube.com/watch?v=QFynhHBPzm4&feature=youtu.be
http://i.imgur.com/i7KJeJG.jpg
http://i.imgur.com/jOtxWlb.jpg
Here is a tutorial on how to do it.
http://www.reddit.com/r/DestinyTheGame/comments/2b80fh/hidden_area_glitch_seraphim_vault/
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I found this location just now, too. Of course, it looks like I'm extremely late. Bunker RAS-2 is located in that one building in Old Russia's Forgotten Shore; it's that one dilapidated building that has Rasputin's voice speaking through a speaker. In that building are stairs that go down a few floors......once you enter, you'll encounter a Hallowed Knight and one "Celebrant of Oryx". The Celebrant is practically a bullet-sponge.....personally I was let down when nothing great was left after I defeated him. Otherwise, the bunker itself has some interesting, high-tech stuff, though sadly none of it is interactive. There are diamond-shaped pods or whatever that are marked in Cryllic, words I can't translate, plus I can't type them out with my keyboard. There's a fancy kiosk beside the one in front of you, as well as another one on a wall beside the pod, and even some boxes that have that yellow-ish wrapping underneath (kind of like the stuff you'd see on the Moon). Oh wow.....just now I checked the two pictures in the OP and saw that this location could go deeper. Well, I wouldn't know since I never got to play the Beta. How much do you want to bet this stuff might be expanded in the upcoming DLC? But only time will tell on that one....