Martin Peres is a French developer now working on the Nouveau driver and in particular has been focusing on developing the power management architecture based upon the reverse-engineering work of other Nouveau developers. This morning before leaving for XDS in Toulouse he announced his Nouveau power management work that includes support for parsing the NVIDIA BIOS for the necessary power management bits (with the NV40 to NV96 ASICs) and then voltage and clock settings for the NVIDIA graphics cards.
While this is a great milestone, this Nouveau power management support isn't yet endorsed for end-users and is not yet ready to be merged. Besides the clock and voltage adjustments needing to be tested on more GeForce/Quadro graphics cards, support for adjusting the memory timings still needs to be done but is currently being reverse-engineered from NVIDIA's binary driver by another developer, and then support for implementing fan control support.
Details on this Nouveau power management patch and how to test it out can be found on the Nouveau mailing list. This code can also be pulled via Git from PathScale's power management Nouveau tree. PathScale previously offered up free NVIDIA Fermi graphics cards to those open-source developers looking forward to working on supporting the new GeForce 400 series graphics cards.