I agree with the sentiments of needing a richer UI for web applications. Why, however, have we focused on Flash rather than Java for such applications???
I know little about Flash for web applications, so I am happy to be convinced either way.
My rant on Java, however, is that I like think the Java language, UI toolkits and back-end communication toolkits (e.g. XML APIs in 1.4) and they provide scope for very well written applications. Furthermore it seems far more open than Flash with multiple vendors providing run-time-environments. I think that Java deserves (another?) run as a browser (and handheld) based application environment. I would like to be convinced that Flash is just as good for web applications (seriously, no sarcasm intended).