Earlier this month, Sun engineers proposed extending the language for Java 7 to include closures and local functions. In his blog, Neal Gafter wrote:
My take on it is this: in the real world, many Java developers are still not allowed to use Java 5 language features like generics (though that's likely to pass within the next year). Language changes just fragment the community and put up barriers to free Java implementations like Harmony, Eclipse, and gcj. As a developer I completely understand the irresistible drive to put in fresh new stuff, and I'm very good at coming up with perfectly plausible and logical reasons for it (I hope my manager isn't reading this). But Java language changes have a terrible and long lasting ripple effect on everybody down the chain. If anybody else besides Sun were proposing this, Sun would have a cow. Surely, those language developers can find much better things to do with their time.
Java 5 changes were bad enough; let's not repeat the mistake. If you want to program in Ruby, then program in Ruby and be done with it, but leave Java the language alone.