In the newest set of ATI power management patches that are available from his personal FreeDesktop.org directory is a patch-set that can be applied against the drm-radeon-testing tree and it begins to utilize the I2C support (also introduced in the Linux 2.6.34 kernel for the ATI DRM) for poking the thermal chips.
Namely these thirteen new patches implement GUI idle IRQ support, support for changing the GPU clocks when the engine is idle, support for turning down the number of active SIMDS when running in a lower power stage for the ATI R600 ASICs and later, and new ASIC specific callback functions.
While this is a good step forward, still on Alex's plate is support for resetting the GPU clocks to the default when the kernel module is unloaded, module support for hwmon i2c thermal chip drivers, hwmon support for monitoring the core temperature and fan speeds on select ATI R600/700 (Radeon HD 2000/3000/4000 series) graphics cards, more robust power state selection, and allow power state selection to be tied to external events such as plugging/unplugging your notebook. Some core areas that also still need to be hooked in is support for memory re-clocking, changing PCI Express lane settings, and voltage adjustments.
Alex announced this newest ATI power management work moments ago on the DRI development list.