Learn Python The Hard Way is a new free eBook by the most epic Zed Shaw, born out of (I think) frustration with other teaching methods in books. I know it’s not Ruby, Rails, or a combination thereof, but Python and Rails live in a very similar open source, develop/learn in the open community, so it’s worth noting. Also Ruby programmers more than anyone should be open to learning other languages to improve skills in their own. Also, if you want to work at Google, this is probably a good thing to check out.
And as I say on my other site, hey, free is free