I think the driver argument is a bit self defeating, if NV has better drivers now, then they can only improve a little. Whereas if ATI drivers aren't as good, then there's a lot of room for improvement... right? So, if you're betting on a card "getting better" it would be the ATI card.
Anyway, drivers are fine for both companies, but it does seem NV has a bit better SLI scaling which is driver related. Although, CF does well anyway.