The 285.03 Beta Linux driver is this new release and it fixes some image corruption, improved performance of the RENDER extension for GeForce 400/500 "Fermi" GPUs, and addresses a bug that causes the X Server to crash after a VT switch. This driver also supports OpenGL 4.2.
Download links and more information is available from this Phoronix Forums thread.
NVIDIA's Christian Zander has also finally commented on the lack of Linux overclocking support for GeForce 400/500 GPUs. Unfortunately, it doesn't look like we will see Fermi overclocking support under Linux by the binary driver in the foreseeable future.
FERMI GPUs are very complex, with elaborate clock trees and memory interfaces (e.g. GDDR5, EDC, ECC, etc.). The NV-CONTROL overclocking interface, on the other hand, is quite naive. In order to properly support clock manipulation on FERMI and newer GPUs, a fair amount of work will need to be done in at least the X driver, NV-CONTROL and nvidia-settings to overhaul the overclocking infrastructure. I believe on Windows, a lot of this type of functionality was moved outside of the driver for that reason.
We do have a bug tracking this RFE internally, and I expect we'll get to it eventually. But given ever-increasing hardware/software complexity, general driver quality concerns and other long-standing feature requests (such as the long-neglected RandR extension), it's hard to justify the effort for a small subset of the NVIDIA Linux graphics driver user base at this time.
This in fact is bad news for seeing overclocking support by the NVIDIA Linux driver for any future GPUs. If Fermi is already too complex and isn't getting overclocking support any time soon, don't look to see the GeForce 600 "Kepler" GPUs when released by year's end to have overclocking support either. Just hope that Kepler isn't too complex for other Linux features to go unsupported outside of the OS-independent shared code-base.