Actually, RBP is not a patterns book at all. It takes a more "on the ground" approach to improving your Ruby skills by walking through real problems. The general idea was to identify some areas that folks struggle with in Ruby and show how experienced Rubyists might attack problems in that area. So it reads more like a series of code reviews than an abstracted set of generalized patterns. In my experience, this is a more practical way to approach Ruby as many patterns from Java can be a bit overkill when ported to Ruby. That having been said, many of them do carry over, and for that, I'd like to recommend Russ Olsen's "Design Patterns in Ruby". I've just started reading that book, but I've heard great things about it.
Have a look at the book's sample chapter to get a feel for the format, and feel free to get back to me if you have any more questions