How good is the shader code?

I am interested in the new shader code that you can buy into, but how good is it? What hardware will support it? I have played with Quake3 arena and the shader code. I also found a blurb about shader code for opengl. Of course the two do not match, but what I was wondering is how refined will the shader code be? Is it going to Q3 easy to use? Is is going to be a script extension? Maybe this is answered somewhere else and I failed to find the link. Is it going to be a radical change from the current engine?

Thanks,
Frank