I got the stripes on my old 4850 setup as well as my new 6950. However, I distinctly remember reading that someone with an nvidia card (I think it was a 560ti) was also getting the lines, so it may not be an AMD only issue.
And like Mazex said, they mentioned that with the "major rewrite of the graphics code" many of our issues would be cured; flickering shadows, horizontal stripes, memory leaks, crashing etc.
But I must say, it's very distracting
