The creator of GeForce cards has released a new set of OpenGL 4.3 graphics drivers in beta version for developers. To play with OpenGL 4.3, a GeForce 400 / 500 / 600 series is required.
More information about NVIDIA OpenGL 4.3 drivers can be found HERE.
R306.63 is based on the dev branch r304_83-34 and exposes 335 OpenGL extensions (GL=309 + WGL=26).
Source: Geeks3D forum