Instance rendering of DirectX 9.0c with OpenGL API

DirectX 9.0c supports Shader Model 3.0.
According to the NVIDIA Shader Model 3.0 introduction, an “Instance API” is added to the New Shader Model. How to use it with OpenGL? Are there any OpenGL extension doing with it?

About the need of having instance in GL:;f=3;t=012910;p=