Hybrid SLI will bring a dual display to a SLI concept and more importantly, it will be able to shut down your discrete graphics card and save you some power.
It will theoretically make the PC a bit less noisy as the single integrated chipset can take care of two displays.
Well, if you want Hybrid SLI then you need to load a discrete graphic and a chipset graphic; but this is only if you game.
Once you get back to your Firefox of Internet exploder, the discrete graphic shuts down and integrated chip takes care of the PC. All clear now?