I agree that most of the Java web bits (including pretty much all the popular web frameworks) are, for lack of a better term, enterprisey crap. It saddens me a bit that GWT isn't more popular - there's a lot of innovation and power there that gets ignored simply because the framework's written in Java. IMHO, Rails and Django et al are just kind of standard web MVC frameworks that happen to be implemented on fun-to-write languages: the only thing out there that has the real "right" approach to web _application_ dev is GWT, which is fundamentally difference from all the rest (per the Google Maps/Wave team, Wave would not have been possible without GWT).
The most "fun" Java web development framework, IMHO, is Stripes. I think what sets it apart is the lack of enterprisey crap - it's simplicity is refreshing, but it's still powerful enough to be useful.
I say this as a disheartened Java programmer. I've recently been involved in a Rails project and a couple of Django projects, and then jumped back into Java. The difference in energy is amazing. Who would make something like this for Java? What would its success path be? Acceptance into an Apache incubator and then into "Commons?" Spec JSR-123987 finally being accepted by Sun/Oracle five years after its written?
I know this isn't a new revelation and I'm far from the first person to bemoan the stale, slow death of Java - but I'm sitting at an airport terminal with nothing better to do, and it's raining out, I'm depressed, and probably shouldn't be posting to HN. :)