Vaadin is actually hosting a purely GWT focussed, not the first one, but it is a long time since we had a GWT conference, and Joonas (from Vaadin) shared some stats: we have 600+ attendees in San Francisco and in Frankfurt together, Frankfurt being sold out.
Ray Cromwell just held the keynote on the gwt.create conference in San Francisco and shared some quite interesting insights on where GWT has come from and how it is moving forward.
So the main challenge in web development changed, and GWT being used so widely at Google, will move forward as well. While speed is going to improve further (Google is still working very hard on the compiler, improving split point generation, fully integration of the closure compiler and much more), the main magic (from my personal view) is happening in the JS inter-operation.
There are really many powerful JS libraries, and modern web development uses them all. The GWT team is working on seamless integration of JS libraries, from lightweight wrappers (say goodbye to JSNI and overlay types) to zero effort JS interop, where the required Java interfaces get generated auto-magically for the JS libraries you drop into your project. And best of all – those libraries should be used un-minified in development and will be parsed by the GWT compiler and get all the optimizations the GWt complier is great at. This means that you can drop the complete jQuery library into you project, but only the JS you use will find its way into your application.
The next major GWT release is expected to come mid 2014 with full Java 8 support and hopefully a bunch of the new magic demoed today.