Thanks to Mark Erikson for significant contributions and improvements made in this new release. Mark and I filled out several additional classes and methods, and made some improvements to the basic implementation style. This new release changes a few APIs from our previous 0.1 release, but Java compile-time checking should help you find any required changes very quickly. Some of the new capabilities include the ability to draw new shapes (box, polygon, polygon outlines, circles) and extrude them (make 3D solid or translucent shapes), improved camera controls, callback handling for "picking" primitives (e.g., to click on an extruded circle--a cylinder drawn vertically from the Earth's surface--and get a callback to tell you what you clicked), more input events (we now support but have not fully tested touch events), more Imagery and Terrain providers, methods to adjust imagery colors (e.g., saturation, brightness), Materials handling, some CZML support, and some SkyBox support!
You can see the samples running here: http://richkadel.github.io/cesium-gwt/cesium-gwt/cesium-gwt.html
And you can take a look at the samples here: https://github.com/richkadel/cesium-gwt/tree/master/cesium-gwt-test/src/main/java/com/harmonia/cesiumsamples
An interesting comparison (for example) is to look at the Polygon example from Sandcastle and Cesium-GWT Sandcastle:
Or check out Camera.java for another interesting comparison.