A new SDK called RubyMotion lets you develop iOS apps in Ruby. I bet there are a lot of people who will be excited about it, but I can't imagine many iOS developers think it's a good idea. Why would you put another layer between you and Apple's APIs? How do you know the Ruby layer will stay up to date? To me, writing iOS apps in Ruby makes about as much sense as writing web apps in Objective-C. Want to write in Ruby? Build a web app.