I managed to snag an early release copy of MacRuby: The Definitive Gude from O’Reilly books.  While for a tech book it’s relatively short, (209 pages and the last two chapters are still “todo”) it seems to be a great reference volume for the Ruby programmer.  Now, this is my first Ruby book, so I must admit i was clinging on to the Cocoa syntax of the book—which is what i like about this book.  Not only does it provide you with how to do something in Ruby, but also (when needed) gives the Cocoa counterpart.  

The only thing I didn’t like about this book is it wasn’t a traditional “how-to” programming book where you start with a simple project and build on it adding more and more features and functionality as you advance through the chapters. There are a few tiny examples of a complete application, but a lot of it revolves around looking at/tweaking the code provided with the book. This is not a problem whatsoever, just not really targeting my preferred learning style. Hence, I’ve labeled this a reference book—and a good one at that.

If you have some Ruby experience and want to leverage it on top of Cocoa for OSX programming, i would recommend this book.  Myself? It’s piqued my interest enough to want to grab a book on Ruby itself.