I'd suggest learning Ruby before picking up a Rails book. While Rails books cover basic Ruby syntax it could leave you high and dry when looking to expand.
Personally, you don't even need a book. Check out
http://ruby-lang.org/, go to the tutorials on the right, and then install it on your system. Then, install rails and just poke around in the community (irc.freenode.com #ruby-lang and #rubyonrails) and API docs.
The community is really what helps within every language, not necessarily books. Or, you could even ask for help in the IRC channels on where to get started, they would be more than happy to assist you.
I think of TFL as more of a XHTML/CSS hub or a way to seek general advice; programming languages don't really seem to flourish as much here.