they will be making motherboards with 2 PCI Express 16x slots, but not AGP
Nvidia is making a technology called SLI, where 1 video card processes the bottom of the screen, and 1 processes the top to make it faster
you could also plug a seperate monitor into each video card, so that it runs a lot better than people with 2 monitors in 1 video card
That is actually old technology - Voodoo PCI cards were doing that years ago with the advent of 3d acceleration in gaming. You would run one of these cards with your normal 2d card however you could run two voodoo cards in conjunction with your 2d card and the two voodoo cards would draw alternate scan lines (Scan Line Interleaving - SLI) on the display effectively only handling half of the display each and allowing them to tackle the 3d data twice as quickly.
Those dual-AGP boards were horrible! I never liked them! The negotiation between the two apatures was terrible, and they were practically worthless for real-time editing. The only thing they were decently good at was processing dumps.