I know many SLI users who have two displays or at least a display and a flat panel HDMI / DVI capable screen and as soon as you enable SLI you simply lose the second display. This is here to stay but we did learned that the professional Nforce SLI chipset can cope with that and will let you have two or more hardware accelerated displays.
I think the rest of the people using the normal SLI will have to learn to live with a single display in SLI mode or with dual display when you turn the SLI off.