Earlier quoted context omitted.
I'm one of the authors of the book. You don't need to know any RoR. There are a couple chapters where we use some Ruby (Jekyll and Cucubmer-driven Selenium Testing), but we walk you through getting things set up properly if you want to use them.
Does that mean that whenever you recommend server-side solutions that the server must have Ruby set up? [OT question that has blocked this PHP-hobbyist from dabbling in RoR: do professionals ever add a new functionality as part of a web app via RoR when the bulk of project has already been built with something like PHP? (looking for motivation to start some experimentation in Ruby)]
The core of the project I'm working on is built in PHP. However, we found that there were a few things that would make more sense in RoR, and there are many features in the future that will be better served as RoR apps. Basically, we are using mod_proxy to redirect to the Rails app.
If you'd like to talk more about it, I'd be more than happy.