iOS programming has a hard time becoming popular to the masses. RubyMotion will give a little more fun to this task.
Objective-C is a nice language, but if you come from a Java/.NET background - as most developers nowadays are - you may find it very difficult to understand: weird syntax, very verbose, etc.
RubyMotion is an implementation of Ruby based on MacRuby that compiles, thru LLVM, to machine code executable on iOS.