Obviously this article just scratches the surface of Ruby and how it can be used to learn about writing object-oriented software. Although there are several books on Ruby, my personal favorite is still Programming Ruby: The Pragmatic Programmer's Guide (Addison-Wesley, 2000, 0-201-71089-7) by the The Pragmatic Programmers, Andy Hunt and Dave Thomas. The first place to visit though is the main Ruby site, because that's where you can find the places to download Ruby, as well as a wealth of articles and tips about using Ruby.
Should experienced developers bother to look at Ruby? Yes, for the simple reason that Ruby puts the fun back into software development. Somehow or other Ruby manages to embody my philosophy that software development is meant to be fun. If it isn't, the process is wrong. Even if most of your work is in C++ or Java, Ruby can be a great tool for trying out ideas that you can later implement in your development language of choice.
Editor willing, later articles in this series will cover things like Test-Driven Development with Ruby and Internet programming with Ruby.