Nvidia added a particularly useful feature to their Release 180 driver, SLI Multi-Monitor Support.
Download the NVIDIA® GeForce® Release 180 driver to enable NVIDIA® SLI® Multi-monitor
support, giving you the ability to use two monitors with your GeForce® graphics cards in SLI mode. Now you can easily switch between multi-monitor desktop mode and full screen 3D gaming [...]
Update: Thanks to Dragon’s tip we are currently undergoing testing of Nvidia’s newest driver.
The short answer is you can’t. But for a dedicated enthusiast it is possible…
When you enable SLI it disables all but one video port (on the SLI bridged cards). This is fact. But there is a way around this limitation by having [...]