Back in February around the time of FOSDEM, AMD had released the R500 3D programming documentation that allowed the open-source community to achieve initial OpenGL R500 acceleration just a month later. At that time we were told the R600 3D documentation should be out in roughly a month, but that never ended up materializing.
Since then we've been told the open-source R600 3D is their leading focus and that they're working to provide the needed documentation or source-code (either a straight-up Mesa implementation or internal AMD software projects like TCore and KGrids), but due to their limited staff and being burdened with intellectual property issues, it's been a slow process to say the least.
In late June there was an initial R600 Direct Rendering Manager, but it was without any 3D support, and then earlier this month we found out that they're close with their R600 DRI support. In late August we also learned of initial 3D support for the RV770 when running off their internal code-base. Now though AMD's Alex Deucher has updated his personal blog to reflect the current situation.
Alex Deucher and Matthias Hopf have figured out the documentation that's needed in enabling 3D support along with writing the documentation and initial code, but the tough part is the intellectual property review. Alex writes, "So when will all of this get released? I can’t say exactly. Soon I hope."
Alex details that the initial code release will likely contain the r600_demo program for sending command buffers to the DRM, 2D EXA acceleration support, X-Video support, and the Mesa R600/700 driver. The actual documentation will then follow.
While "soon" could be interpreted in a number of ways, it would be feasible to think that there could be Mesa 3D support for ATI graphics cards up through the Radeon HD 4800 series by Christmas. We can't imagine it being delayed much longer than that... You can share your thoughts in the Phoronix Forums.