Ruby is a great language for building web applications and manipulating text but it's also the best language to interact with your favorite Mac apps or even build a new app to sell on the Mac App Store. I will demonstrate how to build a simple GUI app in MacRuby and discuss the benefits and drawbacks of doing so versus using RubyCocoa, Objective-C, Objective-J, or Java. I will also discuss the roadmap for MacRuby 1.0, scheduled to be released later this year.