Wow. Quad SLI sucks. LOL. And I don't think more mature drivers are going to help the problem very much...
Great review guys! Thanks!
There's a more comprehensive review of quad sli at Firingsquad that sheds quite a bit of light on the issue.
FS Quad Sli review
Basically, the driver overhead for quad sli holds performance back such that at lower resolutions, normal sli and even single cards perform better. As they indicate, it's only when using very high resolutions with 8xAA/16xAF that quad sli begins to shine. In fact, based on their benchmarks, the two quad setups have a 20-50% performance advantage over even the best normal sli or crossfire setups using such settings.
For instance, in HL2LC 2048x1536x32, 8xAA 16xAF
7900GX2 quad: 55.2 fps
7950GX2 quad: 54.8 fps
7900 GTX sli: 41.9 fps
x1900xtx cf: 37.1 fps
in Quake 4, same settings:
7900GX2 quad: 61.1 fps
7950GX2 quad: 60.8 fps
7900 GTX sli: 43 fps
x1900xtx cf: 35.6 fps
similar results for FEAR, Oblivion (bloom), etc.
With only 4xAA, the normal sli/cf configurations dominate even with resolutions in the range of 1600x1200.
So if you are not going to use above 4xAA with high res, you won't see any benefit to quad sli at all, and may even see a decrease in performance. If, on the other hand, you are going to run some ultra high resolution with 8xAA, you will notice a definite improvement.