Right now you can get similar behavior with anonymous inner classes, but it leads to more clutter than necessary.
This demonstrates another good argument in favor of java - it is always evolving to make programming in it more enjoyable. It was difficult to use collection classes at first, but version 1.5 introduced generics. It sucked to use the iterator pattern with collections, but now java has a "for each" loop. It sucked not having enums, but now Java has them too, etc. Not to mention that every new Java release brings a ton of new library classes and enhancements.
Its unfortunate few of the web hacker types see Java as anything but an "Enterprise" language. Admittedly, JSP (and even JSF) sucks. So the negative wrap that Java gets as a web development language is understandable.
But I think GWT will change that eventually... Build and build, Unit test, and never worry about browsers or the nasty stuff typically related with Ajax-centric development. To me that is worth its weight in gold.
It alleviates some of the cross-browser headaches, but doing anything nontrivial can still hit browser differences, especially with styles and layout.
The only viable browser-worry-free platform seems to be Flash right now.
Lets hope the bugs continue to get ironed out. I know 1.4 will fix quite a few of the minor things.
I think the big deal is the RPC stuff with GWT. While it still has a way to go in terms of customizability, it is extremly powerful none the less. As far as Flash + GWT, I think its pretty sweet doing asynchronous calls via JSON messages between the two. Quite a powerful combination..
You say this as if it was a good thing. Consider the effort, months or years from now, in reading, understanding and modifying all that generated boilerplate.
A better language does not require the boilerplate in the first place.
A Java IDE in a sense "knows" what you're writing and helps you avoid making mistakes while you're coding.
People complain about too much boilerplate code in java - that's true, but it can actually be a good thing in the same way comments can be a good thing, and IDEs generate all the boilerplate for you with just a couple of keystrokes (whereas comments don't write themselves).
I'm curious whether the Java bashers out there have ever used a good IDE like Eclipse or IDEA for any extended period of time. Because if you're using a text editor like emacs, programming in Java can seem ridiculously difficult. Conversely it might seem ridiculously difficult for a person accustomed to an IDE to use a text editor for a scripting language.
Coding Java without an IDE is like trying to control the space shuttle with a steering wheel. Once you've mastered all the features of an IDE, however, (which can take years, but then again so does learning emacs) programming in Java becomes a breeze and you get all the benefits of static typing (with the safety and tools it enables) and the vast Java libraries with no extra difficulty coding compared to a simpler language.