Unless HardOCP are badly wrong in their reporting, those projectors are Acer 720p jobs that used 'CRT connectors' (aka: VGA or D-SUB) and not DVI.
http://www.hardocp.com/article/2010/01/08/nvidia_3d_surround_multidisplay_gaming_editorial
Although Kyle Bennett has my full support (for whatever that is worth) for his last comment:
For god’s sake NVIDIA, if you pull this bullshit where 3D Surround "games" will not work on Eyefinity configurations, we are going to beat NVIDIA down repeatedly and publicly for harming the PC gaming industry. Keep those crappy proprietary PhysX policies, but if you start messing with OUR multi-display gaming and not letting it remain "open platform," I will personally lead the mob with the burning torches to the castle gates. And we will be fully prepared to use the torches. I will personally lead a boycott of NVIDIA products if I see NVIDIA harm multi-display gaming in the marketplace through an IP grab. Multi-display gaming belongs to gamers, not NVIDIA.
I had talked to someone that went to the conference that talked to them and they said it was using the two DVI on one card and one DVI on the second card.
As you can see in this pic on the projector setup.
Those look like DVI to me :rockout
Also yes so far you will need to run it in SLI but like I already said that is still a cheaper solution then buying DP monitors. DP monitors are not cheap and for most people that have 2 monitors already they don't like the idea of miss matched displays. Or they go for the active adapter that soooooo many people are having issues with still.