Question: Is it possible to develop an application in groovy using GWT components?

Luis

Answer: 
If you want to use Groovy on the server-side and GWT for the UI, that is certainly possible. You can use Grails (a Groovy web framework on the server), and the [Grails GWT plugin](http://www.grails.org/plugin/gwt) to help you integrate GWT with this framework.
I have also wondered this, as it would be very nice. Vaadin essentially does this and you can use their plugin: <http://grails.org/plugin/vaadin> 

Doing it this model, though, it is compiling components into Javascript and delivering from the server. But unlike GWT components, these are calling back to the server every time you touch the API (though of course with Vaadin you can use GWT components as well).