Since it figured so heavily in the solution I described in my previous entry, I thought I'd update the featured area part of my site to point to the Pragmatic Programmers, Programming Ruby 2nd Edition.
I highly recommend this book for those who want to learn and who want to use Ruby. It features a good tutorial/introduction to the language, and a great reference. The 2nd edition is much more comprehensive than the first edition and includes topics not found there (e.g. Rails, Gems, and Rake to name a few).
Finally, one of my favorite things about this book is that you can buy it dead tree or pdf (I bought both). If you are curious about Ruby, this is the best place to start IMHO.