NVIDIA has released a WHQL certified graphics driver for all GeForce cards (6, 7, 8, 9, 100, 200, 300, 400, and 500-series desktop GPUs as well as ION desktop GPUs). This driver exposes OpenGL 4.1 and OpenCL 1.1 functionalities. For OpenGL 4.2, try this beta driver: R280.28.
R280.26 is based on the branch r280_11-1.
R280.26 WHQL Downloads: