OpenGL demos taking advantage of Shader Model 4

[Stefan]

Naixela released two demos "geometry shader painterly rendering" and "geometry shader tessellation" taking advantage of Shader Model 4 (inclusive source code).

Found another one:
Integrator's GPU Particle System Demo

afaik GL_EXT_gpu_shader4 and GL_EXT_geometry_shader4 are only for NVIDIA cards, however as opposed to DX10 apps you can run them in Windows XP