I've thought several times about trying to learn the basics required to build an OS X application.  In the past, this meant either going with Java or Objective-C, neither of which I have much experience with.  I've heard a couple people mention RubyCocoa in the last couple of months, but I never looked into it to see what it was all about.  Thanks to Peter Cooper, of Ruby Insider, I've been enlightened and now know that RubyCocoa's goal is to allow OS X applications to be built with Ruby, which in hindsight shouldn't have been very hard to figure out. Although I don't have the time at the moment, I'm certainly going to add a "checkout RubyCocoa" task to my "stack". 

Peter offers the following links:

• Your first few days with RubyCocoa
• RubyCocoa Screencasts
• RubyCocoa Homepage