Looks like the process of editing takes much longer than I realized. The past 6 months we have been in the editing process. One big delay was that the book was on hold for almost 4 months as the editor was busy. Additionally gaining rights to some of the film images was a longer-than-expected process. Then once a new editor was on board, we discovered the book was 150 pages longer than it was profitable to print. After a quick re-write of some sections, removal of others, and another round of editing, I am happy report to we are moving forward again and progressing with layout. All the images have been cleared for publishing, including a large handful from Disney/Pixar and Sony Imageworks, who graciously granted the rights to reproduce them in the book.

Currently the book will release around Siggraph. I am very much hoping for a pre-Siggraph release but we may not make it, in which case it should be out shortly after, barring some (more) unforseen delays.
For those who have been kind enough to pre-order, they have received repeated emails about the delay. Now there's the behind-the-scenes story.

Removed sections of the book will be available on the companion website:
www.illuminated-pixels.com
along with sample scene files from imagery in the book, links to contributor websites, and anything else lighting related which looks interesting or useful.