For those curious about the state of various features for the range of ATI/AMD Radeon GPUs on the open-source Linux graphics driver stack, the feature Wiki continues to be maintained.
While OpenGL 3.0 is now supported by R600g
for all hardware, there remains a lot of outstanding TODO items
with a number of features having yet to be completed or fully implemented.
If you're interested in an overview of feature support for the different generations of Radeon hardware when using the open-source Radeon driver, see the RadeonFeature page
Among the notable items not completed is that video decode support (using the 3D engine with shaders as opposed to UVD access) is still considered a work-in-progress, hybrid graphics is just "mostly" implemented, stippled primitives / smooth primitives support is TODO, tesselation and geometry shaders for modern hardware, Hyper-Z for modern hardware, OpenGL 4.x capable hardware is still capped at OpenGL 3.0 compliance, no CrossFire support, OpenCL is an open item, and the Radeon HD 7000 series driver still requires a great deal of work all-around.