First, sorry for my bad English.
GL_NV_conditional_render does not work: it renders object even if occlusion_query reports about his invisibility.
Cards HD5970 and HD5650
PS: occlusion_query works fine.
For sample: flares draws through walls
Sorry for the delayed response - we just saw your post. This has been reported by multiple people and we are looking into it. We'll get the fix into a public driver ASAP.