Apparently the book is still forthcoming, since I cdn't find an entry for it on amazon, and what looks to be the author's blog (http://themusicofthelordoftheringsfilms.blogspot.com/) still refers to it as "upcoming" (the full title of his blog being THE OFFICIAL AUTHOR'S BLOG FOR THE UPCOMING BOOK THE MUSIC OF THE LORD OF THE RINGS: A COMPREHENSIVE GUIDE TO HOWARD SHORE'S SCORES).
I'm a bit surprised by the idea of listening to film scores in concert, like they were today's equivalent to the classical symphony. But then over the years I've found that my friends more and more buy soundtracks and listen to them a lot (mainly as background noise during gaming), whereas I'm unlikely to buy a soundtrack except to remind me of the movie (the sole exception I can think of being A FISH NAMED WANDA, where I'd just really liked the music).* Apparently I'm in a shrinking minority here. I don't know if Mr. Adams' comment about hints of Sibelius are right or not, not being familiar with the Finnish master; all Shore owed to Wagner, I wd think, is the idea of the liefmotifs (admittedly, a major element in Shore's three soundtracks). The Mahler I can see; there's that general feeling of 'Symphony from a New World' in places. I guess we'll see whether or not the eventual book is something the non-musicological can follow and enjoy.
In any case, it seems to be a timely topic: in addition to this book there are at least three others either recently out or soon to be released about Tolkien and music, none of which unfortunately I've seen:
First, there's Matthew Young's PROJECTING TOLKIEN'S MUSICAL WORLDS, which I haven't bought yet because I thought the price ($54 for 92 pages) prohibitive.**
Also, there's the recently released MUSIC IN MIDDLE-EARTH, the latest collection from Walking Tree Press, ed by Heidi Steimel & Friedhelm Schneidewind. Apparently, from the amazon.com entry, this is a fairly wide-ranging collection, but details are lacking.
Finally, there's the forthcoming book by Bradford Lee Eden, due out from McFarland next month (just too late for Kalamazoo, unfortunately).
Apparently an idea whose time has come.
*I wd have bought the LAIR OF THE WHITE WORM for the lively performance of a traditional dragon-song in it, but cdn't find it available.
**there is an informative review, by Jason Fisher, in MYTHLORE (vol. 28 no. 1-2, pages 175-179)