Here is Christina and Wayne's blog post:
http://wayneandchristina.wordpress.com/ ... -part-two/
This really sounds exciting:
The Lord of the Rings is of course a much longer and more complex work than The Hobbit, and has a different nature and history. It was written over a greater length of time, and with more false starts and wrong avenues; and it never had drawings or paintings made for publication, or to include in a ‘home manuscript’ the author could show to friends, except for a few maps and ‘facsimile’ inscriptions. Instead, the bulk of the art behind The Lord of the Rings consists of sketches, plans, and maps which Tolkien made to aid him in his writing – more numerous, more miscellaneous, and usually less ‘finished’ than the Hobbit art – and because these images were made as the story was conceived and revised, we needed to relate them not to a comparatively short text like The Hobbit, and not only to the published Lord of the Rings, but also to Tolkien’s drafts as published in The History of Middle-earth or, more directly in a few instances, as preserved among his papers at Marquette University.
In discussion with HarperCollins, we chose to document Tolkien’s art for The Lord of the Rings in its entirety, as we had earlier his art for The Hobbit, to the extent that it survives and is known to us or to its curators. It was always clear that The Art of The Lord of the Rings would be a longer book than The Art of The Hobbit, though when we began we couldn’t guess how long it would be, and as we worked, more images came to light than were on our initial list. Our new book will be 240 pages long, compared with 144 pages for The Art of The Hobbit, and will contain 182 pieces of artwork (plus 11 details), all of it in colour, versus 104 pieces (with 2 sets of details) for our earlier book. In appearance, the new volume will be similar in design to The Art of The Hobbit, in a large square format, but this time with no gatefolds as they didn’t seem warranted. HarperCollins are working on a handsome binding and slipcase design, shown here in mockup.
Not the final art: trial binding and slipcase prepared by HarperCollins
This promises to be as much a companion to the "History of
The Lord of the Rings" volumes of HoME as to LOTR itself. Really excited!
"Spirits in the shape of hawks and eagles flew ever to and from his halls; and their eyes could see to the depths of the seas, and pierce the hidden caverns beneath the world."
I'll have to check out Art of The Hobbit as well; I must have not been around when that came out. 
