The book in question, Corey Olsen's EXPLORING J. R. R. TOLKIEN'S THE HOBBIT, is forthcoming this fall (Sept 18th release date, just in time for Bilbo's Birthday on the 22nd). This is one I've been looking forward to since I first heard about it a few months ago. I'm not a great follower of podcasts, but I'd seen Corey present a piece on a HOBBIT roundtable at Kalamazoo a year or two ago and been struck by the detail with which he treated Tolkien's poetry, which is usually given short shrift.
What we have with this book is a chapter-by-chapter close reading of THE HOBBIT: nineteen chapters in Tolkien's original corresponding to nineteen chapters of Olsen's explication. I can't go into detail, since it's still forthcoming and it wdn't do to give away the best bits, but I enjoyed it quite a lot and will probably be using it for reference for a long time to come. Corey both scrutinizes specific scenes and follows the appearance of some major themes that recur throughout the book. One specific example I can mention is his treatment of the Riddle-game, since in lieu of some last-minute cancellations, he allowed that section to be read out loud in absentia at this year's medievalist congress. I've never seen as in-depth a discussion of the various riddles that make up Bilbo's and Gollum's exchange, pointing out how they tend to form matched pairs thematically or symbolically, how each works as characterization for the one telling the riddle, &c. I'm not sure that Tolkien intended all themes Olsen finds here, but that can be said of a lot of detailed explication, mine included. In any case, it's really an impressive piece of work.
So, if you're interested in THE HOBBIT you'll definitely want to check out this one.
More later, once the book's actually out.