Ikea is making a bookcase that doubles as a secret door. Or maybe you use their bookcases to construct the hidden passage.
Anyway:
Unless I've misread something, it looks like it's a home made setup using some Ikea Billy book cases. I don't think Ikea is selling the hidden passage concept. They just happen to market the book cases.
Hidden passageways have been discussed here frequently. More important than the hinges which are mentioned and shown, is the means for which the weight and supporting of the swing out part of the door.
The diagonal dimension of the 'plan' view of the book cases makes it hard for me to get my head around. Where the hinge is located, the diagonally opposed corner of the case cannot clear the case beside it.... unless one angles the sides as cord of a circle with the hinge point as its centre or leaves a gap.
I had the same thought, but the case on the right (the one with the booze) is angled. I looked at the discussions and someone pointed out the same thing you did, which prompted me to go to the "Lifehacker" page on the passage.
thge discussion there says: We used two Ikea Billy Bookshelves, and built a 'skateboard' out of casters and some pressed board for the moving shelf to sit on. Then hinged them together, laid out some hardwood for it to roll on, and there you have it. The bar we also built, and it's angled so as to make the door flush when closed without any collisions while opening
Luigi
The picture doesn't really show that clearly, besides, that set-up is such old hat, I hardly paid attention to it.
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