Ruby is a great language, Java is a great platform. With Ruby running on a Java Virtual Machine, you get the best of both worlds.
As a language, Ruby is superior to Java for most general purpose programming tasks, as implied here, here, and here. (Some people disagree, mostly for reasons I have already covered under myths one, two, and three.)
As a platform, Java wins hands down. Until recently, Ruby's platform was simply the interpreter (MRI). Want to know how it works? Read the source code. Java provides a much better platform, including
Plus Java has more implementations than you can shake a stick at, running everywhere you want to be.
So can't we all just get along? I want to live in a world where language preference does not define a programmer. We'll write code in Ruby, or Scheme, or Scala, or Erlang. And we can all live in harmony on a JVM anywhere.
Want to help create this world? Here are some steps you can take: