There are two planned drivers for Radeons in Gallium, r300 and r600, with one winsys, DRM-based radeon. r300 covers r300-r500 hardware, and r600 covers r600-r700+ hardware.
r300 is started, and kind of works for some very trivial cases. It needs a lot more work, but most of the code is there, just broken.
r600 hasn't been started. There's all kinds of problems in the winsys and kernel code that are preventing it from being started.