Ruby for the Objective-C Runtime
MacRuby is an implementation of Ruby 1.9 directly on top of Mac OS X core technologies such as the Objective-C runtime and garbage collector, the LLVM compiler infrastructure and the Foundation and ICU frameworks. It is the goal of MacRuby to enable the creation of full-fledged Mac OS X applications which do not sacrifice performance in order to enjoy the benefits of using Ruby.
You can install the latest stable release or, if you are feeling adventurous, you can install one of the nightly builds . See the wiki for more detailed instructions .