MacRuby is a Ruby implementation for Mac OS X that allows Ruby code to be compiled to native machine code. It uses the LLVM compiler infrastructure and integrates tightly with Cocoa and Objective-C. Some key features include using the same syntax as Ruby but with faster performance due to compilation, ability to build Mac desktop applications that can be submitted to the Mac App Store, and direct access to technologies like Grand Central Dispatch for concurrent programming. The future of MacRuby may involve continued integration of Ruby with technologies like LLVM and GCD.