He's talking about RubyCocoa, which is what OS X comes with, not MacRuby. RubyCocoa uses the Objective-C/Cocoa object bridge, to allow Ruby to talk to Cocoa obj

He's talking about RubyCocoa, which is what OS X comes with, not MacRuby. RubyCocoa uses the Objective-C/Cocoa object bridge, to allow Ruby to talk to Cocoa objects and send messages. MacRuby is a different beast. It compiles with LLVM, is not bridged, and therefore works directly with Obj-C/Cocoa. (Though, honestly, the bridged languages are really pretty good, too. Obj-C bridging is good in general. MacRuby is just sensational.)