In "It's the tools, stupid!, " Patrick Lightbody says: "Patrick Peak came to the conclusion that the main benefit Ruby brings to the table over Java is in the area of the development workflow. This is very true and, in my opinion, is the heart of the Rails vs J2EE/Java/WebWork/Whatever argument. The key thing is, in fact, not Rails, but Ruby. And that's OK."

Part of his summary:
Developer productivity is not to be dismissed lightly. Ruby has a leg up on Java right now because it is inherently a better language. But it is far from a better platform right now, which is unfortunate. So the question is: Which will happen first? Will Ruby get the tools, or will Java get its act together and catch up to Ruby? One, if not both, are bound to happen soon, and no matter what the developers will win.