There's been several DIY versions of these floating 'round the net, and they're now available en masse for approximately 20 GBP from I Want One of Those!
“Bookshelves whilst being terribly useful, have never really managed the style leap into cool. They are after all just shelves. Well not so the Book Shelf however. For this tome is (of course) not a book at all, but a shelf that looks just like one. Simply attach it to your wall (all the bits are provided) and pile your worthy novels on it, and it will look as though your reading material is floating in space, though not space as in the final frontier obviously. This Book Shelf is sheer genius. When there is simply no room for a book case – or quite frankly when there is, but you want something a bit different, use this floating shelf disguised as a sophisticated French novel as your storage solution. Who'd have thought shelving could be so chic?”