I don't want to spam the mailing list, but I feel like I have to answer Scott's question (quoted below).
In general, I'd refrain from comparing my book with others, but in this case IMHO it's clear from the contents that they cover a different scope.
In brief, Jason's 'A Gentle Introduction to ROS' contents are summarized in the first 3 chapters of 'Learning ROS for Robotics Programming', both the first and second edition.
The 'Learning ROS for Robotics Programming - 2nd edition' is closer to other books, like 'ROS by Example', being these two suggested as other books in the link you provided.
You can also see a comprehensive list of ROS books on this wiki
http://wiki.ros.org/Books, that I created a few years ago, when only these two ROS books were available, to the best of my knowledge.
Best,
Enrique