Ok, so I'm still a little pissed at people on the road, but it still applies here. The Gigabyte dual-core solution was all the rage here about what, three weeks ago?
On the lost bandwidth agrument: at the moment, enabling SLI on an nForce4 board splits your single PCIe x16 lane into a pair of PCIe x8 slots. But PCIe, as it currently exists, doesn't fill a single x8 lane, so you don't get a bandwidth drop yet; by the time you do, new chipsets will likely support more than 20 PCIe lanes. In this case, the two cores each get eight lanes of the x16 slot. No, Gigabyte's solution does not provide the ability for quad GPUs. It's nothing more than a one-card SLI solution. The bridge that in other applications is used to link two cards is built directly onto this one. Currently that precludes any chance for quad GPUs. This is exactly the same as any other SLI 6600GT system. It's the same thing. However, if you directly compare benchmarks with a standard 6600GT-in-SLI setup, the 3D1 does slightly better; this should be the case as Gigabyte's card is overclocked from the factory. However, each core only gets a 128-bit datapath.
Is it a cool idea? I guess, but when you consider that you have to stick with Gigabyte for the whole thing (it requires BIOS customisation to work properly on boot), it's really not all that hot.
oh, ok, ill just stick with standard graphics cards :P