From the Final Inside Google Books Blog Post:
Thanks to everyone who’s been a loyal reader of the Google Books Search blog over the years. As part of an effort to simplify our communications channels, we’re retiring this blog and moving on over to the official Google Inside Search Blog. We’re looking forward to continuing the conversation about Google Books search there.
For those of you interested in eBooks, be sure to follow Google Play at play.google.com/+ to learn all about upcoming author Hangouts plus new content, features and releases on Google Play.
The Inside Google Book Search blog began with this post in May 2006.