Both GWT and Wicket are stateful, java object oriented based. GWT is completely client based with features like javascript optimization, CSS optimization, and I\'m pretty new to
It is pretty much apples to oranges.
This wiki entry summarizes some of the similarities and differences, and the start of a strategy for using them together, which I think is an interesting idea.
Wicket is primarily a server-side technology with some built-in Ajax support and hooks for wiring in more Ajax. It does not translate Java to JavaScript like GWT. It maintains state server-side where GWT maintains state on the client.
Both are component-based and to me have something of the feeling of Swing development (though Wicket doesn't seem to feel like Swing to at least one other respondent).