I just discovered that you can use Matrox PowerDesk software on Nvidia Surround to setup virtual monitors, it's similar to Hydragrid on Eyefinity setups but seems to work better.
Finally I can leave my system in surround view 6040x1080 with 4way SLI and use the monitors as 3 individual monitors for applications and maximise/snap to a single monitor!
Also allows to set default open monitor! I've been searching for something like AMD/ATI Hydragrid since I moved from ATI Eyefinity.
I LOVE IT!
For those interested, you just need to setup Nvidia Surround or 3D Surround like normal and then download the appropriate version of PowerDesk.
Windows XP, Windows Server 2003, Windows Vista, Windows Server 2008, Windows 7 x86:
http://www.matrox.com/graphics/en/support/drivers/download/?id=436
Windows XP, Windows Server 2003, Windows Vista, Windows Server 2008, Windows Server 2008 R2, Windows 7 x64:
http://www.matrox.com/graphics/en/support/drivers/download/?id=437